From 289f87fe7074b7876b4e1404b8ce4018e14ab4a2 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Tue, 3 Aug 2021 21:20:58 -0500
Subject: [PATCH 01/26] Initial work towards splitting FilePath

---
 packages/files/_test.pony     | 96 +++++++++++++++++++++++------------
 packages/files/auth.pony      |  3 ++
 packages/files/directory.pony | 24 ++++-----
 packages/files/file_path.pony | 68 ++++++++++++++-----------
 4 files changed, 117 insertions(+), 74 deletions(-)
 create mode 100644 packages/files/auth.pony

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index decf12b1d6..33f0a433ce 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -61,13 +61,14 @@ actor Main is TestList
 
 primitive _FileHelper
   fun make_files(h: TestHelper, files: Array[String]): FilePath ? =>
-    let top = Directory(FilePath.mkdtemp(h.env.root as AmbientAuth,
+    let ambient = h.env.root as AmbientAuth
+    let top = Directory(FilePath.mkdtemp(FileAuth(ambient),
       "tmp._FileHelper.")?)?
     for f in files.values() do
       try
         // Since we embed paths, we use the posix separator, even on Windows.
         let dir_head = Path.split(f, "/")
-        let fp = FilePath(top.path, dir_head._1)?
+        let fp = FilePath.from(top.path, dir_head._1)?
         let r = fp.mkdir()
         if dir_head._2 != "" then
           Directory(fp)?.create_file(dir_head._2)?.dispose()
@@ -110,7 +111,8 @@ trait iso _NonRootTest is UnitTest
 class iso _TestMkdtemp is UnitTest
   fun name(): String => "files/FilePath.mkdtemp"
   fun apply(h: TestHelper) ? =>
-    let tmp = FilePath.mkdtemp(h.env.root as AmbientAuth, "tmp.TestMkdtemp.")?
+    let ambient = h.env.root as AmbientAuth
+    let tmp = FilePath.mkdtemp(FileAuth(ambient), "tmp.TestMkdtemp.")?
     try
       h.assert_true(FileInfo(tmp)?.directory)
     then
@@ -147,7 +149,8 @@ class iso _TestSymlink is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "symlink")?
+    let ambient = h.env.root as AmbientAuth
+    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "symlink")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -192,7 +195,8 @@ class iso _TestSymlink is UnitTest
 class iso _TestDirectoryOpen is UnitTest
   fun name(): String => "files/File.open.directory"
   fun apply(h: TestHelper) ? =>
-    let tmp = FilePath.mkdtemp(h.env.root as AmbientAuth, "tmp.TestDiropen.")?
+    let ambient = h.env.root as AmbientAuth
+    let tmp = FilePath.mkdtemp(FileAuth(ambient), "tmp.TestDiropen.")?
 
     try
       h.assert_true(FileInfo(tmp)?.directory)
@@ -208,9 +212,10 @@ class iso _TestDirectoryFileOpen is UnitTest
   fun name(): String => "files/Directory.open-file"
   fun apply(h: TestHelper) =>
   try
+    let ambient = h.env.root as AmbientAuth
     // make a temporary directory
     let dir_path = FilePath.mkdtemp(
-      h.env.root as AmbientAuth,
+      FileAuth(ambient),
       "tmp.directory.open-file")?
     try
       let dir = Directory(dir_path)?
@@ -413,7 +418,8 @@ class iso _TestFileEOF is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.eof"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = File(filepath) do
         file.write("foobar")
         file.sync()
@@ -436,7 +442,8 @@ class iso _TestFileCreate is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.create"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -454,7 +461,8 @@ class iso _TestFileCreateExistsNotWriteable is _NonRootTest
   fun apply_as_non_root(h: TestHelper) ? =>
     let content = "unwriteable"
     let path = "tmp.create-not-writeable"
-    let filepath = FilePath(h.env.root as AmbientAuth, path)?
+    let ambient = h.env.root as AmbientAuth
+    let filepath = FilePath(FileAuth(ambient), path)?
     try
       let mode: FileMode ref = FileMode.>private()
       mode.owner_read = true
@@ -486,9 +494,10 @@ class iso _TestFileCreateDirNotWriteable is _NonRootTest
   fun apply_as_non_root(h: TestHelper) =>
     ifdef not windows then
       try
+        let ambient = h.env.root as AmbientAuth
         let dir_path =
           FilePath.mkdtemp(
-            h.env.root as AmbientAuth,
+            FileAuth(ambient),
             "tmp.create-dir-not-writeable")?
         let mode: FileMode ref = FileMode.>private()
         mode.owner_read = true
@@ -519,9 +528,10 @@ class iso _TestFileOpenInDirNotWriteable is UnitTest
   fun apply(h: TestHelper) =>
     ifdef not windows then
       try
+        let ambient = h.env.root as AmbientAuth
         // make a temporary directory
         let dir_path = FilePath.mkdtemp(
-          h.env.root as AmbientAuth,
+          FileAuth(ambient),
           "tmp.open-dir-not-writeable")?
         try
           let dir = Directory(dir_path)?
@@ -555,8 +565,9 @@ class iso _TestFileCreateMissingCaps is UnitTest
       let no_read_caps = FileCaps.>all().>unset(FileWrite)
       let no_write_caps = FileCaps.>all().>unset(FileRead)
 
+      let ambient = h.env.root as AmbientAuth
       let file_path1 = FilePath(
-        h.env.root as AmbientAuth,
+        FileAuth(ambient),
         "tmp.create-missing-caps1",
         consume no_create_caps)?
       let file1 = File(file_path1)
@@ -564,7 +575,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       h.assert_is[FileErrNo](file1.errno(), FileError)
 
       let file_path2 = FilePath(
-        h.env.root as AmbientAuth,
+        FileAuth(ambient),
         "tmp.create-missing-caps2",
         consume no_read_caps)?
       let file2 = File(file_path2)
@@ -572,7 +583,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       h.assert_is[FileErrNo](file2.errno(), FileError)
 
       let file_path3 = FilePath(
-        h.env.root as AmbientAuth,
+        FileAuth(ambient),
         "tmp.create-missing-caps3",
         consume no_write_caps)?
       let file3 = File(file_path3)
@@ -588,7 +599,8 @@ class iso _TestFileOpen is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.open"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -612,7 +624,8 @@ class iso _TestFileOpenError is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.openerror"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       h.assert_false(filepath.exists())
       let file = OpenFile(filepath)
       h.assert_true(file is FileError)
@@ -626,7 +639,8 @@ class _TestFileOpenWrite is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.open-write"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.print("write on file opened read-only")
       end
@@ -650,7 +664,8 @@ class iso _TestFileOpenPermissionDenied is _NonRootTest
         // on windows all files are always writeable
         // with chmod there is no way to make a file not readable
       try
-        let filepath = FilePath(h.env.root as AmbientAuth, "tmp.open-not-readable")?
+        let ambient = h.env.root as AmbientAuth
+        let filepath = FilePath(FileAuth(ambient), "tmp.open-not-readable")?
         with file = CreateFile(filepath) as File do
           file.print("unreadable")
         end
@@ -679,7 +694,8 @@ class iso _TestFileLongLine is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.longline"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = File(filepath) do
         var longline = "foobar"
         for d in Range(0, 10) do
@@ -701,7 +717,8 @@ class iso _TestFileWrite is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.write"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.write("foobar\n")
       end
@@ -724,7 +741,8 @@ class iso _TestFileWritev is UnitTest
       wb.write(line1)
       wb.write(line2)
       let path = "tmp.writev"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -744,7 +762,8 @@ class iso _TestFileQueue is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.queue"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.queue("foobar\n")
       end
@@ -766,7 +785,8 @@ class iso _TestFileQueuev is UnitTest
       wb.write(line1)
       wb.write(line2)
       let path = "tmp.queuev"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.queuev(wb.done())
       end
@@ -799,7 +819,8 @@ class iso _TestFileMixedWriteQueue is UnitTest
       wb.write(line6)
       let queuev_data = wb.done()
       let path = "tmp.mixedwrite"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         file.print(line3)
         file.queue(line5)
@@ -840,7 +861,8 @@ class iso _TestFileWritevLarge is UnitTest
         count = count + 1
       end
       let path = "tmp.writevlarge"
-      let filepath = FilePath(h.env.root as AmbientAuth, path)?
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)?
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -861,7 +883,8 @@ class iso _TestFileFlush is UnitTest
   fun name(): String => "files/File.flush"
   fun apply(h: TestHelper) =>
     try
-      let path = FilePath(h.env.root as AmbientAuth, "tmp.flush")?
+      let ambient = h.env.root as AmbientAuth
+      let path = FilePath(FileAuth(ambient), "tmp.flush")?
       with file = CreateFile(path) as File do
         // Flush with no writes succeeds trivially, but does nothing.
         h.assert_true(file.flush())
@@ -888,7 +911,8 @@ class iso _TestFileFlush is UnitTest
 class iso _TestFileReadMore is UnitTest
   fun name(): String => "files/File.read-more"
   fun apply(h: TestHelper)? =>
-    let path = FilePath(h.env.root as AmbientAuth, "tmp-read-more")?
+    let ambient = h.env.root as AmbientAuth
+    let path = FilePath(FileAuth(ambient), "tmp-read-more")?
     with file = CreateFile(path) as File do
       h.assert_true(file.write("foobar"))
     end
@@ -911,7 +935,8 @@ class iso _TestFileReadMore is UnitTest
 class iso _TestFileRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-file"
   fun apply(h: TestHelper) ? =>
-    let path = FilePath(h.env.root as AmbientAuth, "tmp-read-only")?
+    let ambient = h.env.root as AmbientAuth
+    let path = FilePath(FileAuth(ambient), "tmp-read-only")?
     try
       with file = CreateFile(path) as File do
         None
@@ -933,7 +958,8 @@ class iso _TestDirectoryRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-directory"
 
   fun apply(h: TestHelper) ? =>
-    let path = FilePath.mkdtemp(h.env.root as AmbientAuth, "tmp-read-only-dir")?
+    let ambient = h.env.root as AmbientAuth
+    let path = FilePath.mkdtemp(FileAuth(ambient), "tmp-read-only-dir")?
     let dir = Directory(path)?
     try
       let mode: FileMode ref = FileMode
@@ -955,7 +981,8 @@ class iso _TestFileLinesEmptyFile is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "empty")?
+    let ambient = h.env.root as AmbientAuth
+    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "empty")?
 
   fun ref tear_down(h: TestHelper) =>
     try (tmp_dir as FilePath).remove() end
@@ -1001,7 +1028,8 @@ class iso _TestFileLinesSingleLine is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "single-line")?
+    let ambient = h.env.root as AmbientAuth
+    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "single-line")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -1068,7 +1096,8 @@ class _TestFileLinesMultiLine is UnitTest
   ]
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "multi-line")?
+    let ambient = h.env.root as AmbientAuth
+    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "multi-line")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -1113,7 +1142,8 @@ class _TestFileLinesMovingCursor is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "moving-cursor")?
+    let ambient = h.env.root as AmbientAuth
+    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "moving-cursor")?
 
   fun ref tear_down(h: TestHelper) =>
     try
diff --git a/packages/files/auth.pony b/packages/files/auth.pony
new file mode 100644
index 0000000000..d7f57c3107
--- /dev/null
+++ b/packages/files/auth.pony
@@ -0,0 +1,3 @@
+primitive FileAuth
+  new create(from: AmbientAuth) =>
+    None
\ No newline at end of file
diff --git a/packages/files/directory.pony b/packages/files/directory.pony
index cb1e451848..a8aa16b689 100644
--- a/packages/files/directory.pony
+++ b/packages/files/directory.pony
@@ -181,7 +181,7 @@ class Directory
       error
     end
 
-    let path' = FilePath(path, target, path.caps)?
+    let path' = FilePath.from(path, target, path.caps)?
 
     ifdef linux or bsd then
       let fd' =
@@ -208,7 +208,7 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, target, path.caps)?
+      let path' = FilePath.from(path, target, path.caps)?
 
       ifdef linux or bsd then
         var offset: ISize = 0
@@ -247,7 +247,7 @@ class Directory
       error
     end
 
-    let path' = FilePath(path, target, path.caps)?
+    let path' = FilePath.from(path, target, path.caps)?
 
     ifdef linux or bsd then
       let fd' =
@@ -272,7 +272,7 @@ class Directory
       error
     end
 
-    let path' = FilePath(path, target, path.caps - FileWrite)?
+    let path' = FilePath.from(path, target, path.caps - FileWrite)?
 
     ifdef linux or bsd then
       let fd' =
@@ -328,7 +328,7 @@ class Directory
       error
     end
 
-    let path' = FilePath(path, target, path.caps)?
+    let path' = FilePath.from(path, target, path.caps)?
 
     ifdef linux or bsd then
       FileInfo._relative(_fd, path', target)?
@@ -349,7 +349,7 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, target, path.caps)?
+      let path' = FilePath.from(path, target, path.caps)?
 
       ifdef linux or bsd then
         0 == @fchmodat(_fd, target.cstring(), mode.u32(), I32(0))
@@ -373,7 +373,7 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, target, path.caps)?
+      let path' = FilePath.from(path, target, path.caps)?
 
       ifdef linux or bsd then
         0 == @fchownat(_fd, target.cstring(), uid, gid, I32(0))
@@ -409,7 +409,7 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, target, path.caps)?
+      let path' = FilePath.from(path, target, path.caps)?
 
       ifdef linux or bsd then
         var tv: (ILong, ILong, ILong, ILong) =
@@ -440,7 +440,7 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, link_name, path.caps)?
+      let path' = FilePath.from(path, link_name, path.caps)?
 
       ifdef linux or bsd then
         0 == @symlinkat(source.path.cstring(), _fd, link_name.cstring())
@@ -465,7 +465,7 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, target, path.caps)?
+      let path' = FilePath.from(path, target, path.caps)?
 
       ifdef linux or bsd then
         let fi = FileInfo(path')?
@@ -507,8 +507,8 @@ class Directory
     end
 
     try
-      let path' = FilePath(path, source, path.caps)?
-      let path'' = FilePath(to.path, target, to.path.caps)?
+      let path' = FilePath.from(path, source, path.caps)?
+      let path'' = FilePath.from(to.path, target, to.path.caps)?
 
       ifdef linux or bsd then
         0 == @renameat(_fd, source.cstring(), to._fd, target.cstring())
diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index 9e7dd3ed64..000d9e2287 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -54,43 +54,50 @@ class val FilePath
     """
 
   new val create(
-    base: (FilePath | AmbientAuth),
+    base: FileAuth,
     path': String,
     caps': FileCaps val = recover val FileCaps .> all() end)
-    ?
   =>
     """
-    Create a new path. The caller must either provide the root capability or an
-    existing FilePath.
+    Create a new path.
 
-    If the root capability is provided, path' will be relative to the program's
-    working directory. Otherwise, it will be relative to the existing FilePath,
-    and the existing FilePath must be a prefix of the resulting path.
+    Unless absolute, path' will be relative to the program's working directory.
 
-    The resulting FilePath will have capabilities that are the intersection of
-    the supplied capabilities and the capabilities on the parent.
+    Capabilities are as provided, unlike with `FilePath.from(...)`.
     """
     caps.union(caps')
+    path = Path.abs(path')
 
-    path = match base
-      | let b: FilePath =>
-        if not b.caps(FileLookup) then
-          error
-        end
+  new val from(
+    base: FilePath,
+    path': String,
+    caps': FileCaps val = recover val FileCaps .> all() end)
+    ?
+  =>
+    """
+    Create a new path from an existing `FilePath`.
 
-        let tmp_path = Path.join(b.path, path')
-        caps.intersect(b.caps)
+    path' is relative to the existing `FilePath`,
+    and the existing `FilePath` must be a prefix of the resulting path.
 
-        if not tmp_path.at(b.path, 0) then
-          error
-        end
-        tmp_path
-      | let b: AmbientAuth =>
-        Path.abs(path')
-      end
+    The resulting `FilePath` will have capabilities that are the intersection of
+    the supplied capabilities and the capabilities of the existing `FilePath`.
+    """
+    caps.union(caps')
+    if not base.caps(FileLookup) then
+      error
+    end
+
+    let tmp_path = Path.join(base.path, path')
+    caps.intersect(base.caps)
+
+    if not tmp_path.at(base.path, 0) then
+      error
+    end
+    path = tmp_path
 
   new val mkdtemp(
-    base: (FilePath | AmbientAuth),
+    base: (FilePath | FileAuth),
     prefix: String = "",
     caps': FileCaps val = recover val FileCaps .> all() end)
     ?
@@ -100,7 +107,7 @@ class val FilePath
     will begin with `prefix`. The caller must either provide the root
     capability or an existing FilePath.
 
-    If AmbientAuth is provided, pattern will be relative to the program's
+    If FileAuth is provided, pattern will be relative to the program's
     working directory. Otherwise, it will be relative to the existing
     FilePath, and the existing FilePath must be a prefix of the resulting path.
 
@@ -108,16 +115,19 @@ class val FilePath
     the supplied capabilities and the capabilities on the base.
     """
     (let dir, let pre) = Path.split(prefix)
-    let parent = FilePath(base, dir)?
+    let parent: FilePath = match base
+      | let base': FileAuth => FilePath(base', dir)
+      | let base' : FilePath => FilePath.from(base', dir)?
+    end
 
     if not parent.mkdir() then
       error
     end
 
-    var temp = FilePath(parent, pre + Path.random())?
+    var temp = FilePath.from(parent, pre + Path.random())?
 
     while not temp.mkdir(true) do
-      temp = FilePath(parent, pre + Path.random())?
+      temp = FilePath.from(parent, pre + Path.random())?
     end
 
     caps.union(caps')
@@ -139,7 +149,7 @@ class val FilePath
     """
     Return a new path relative to this one.
     """
-    create(this, path', caps')?
+    from(this, path', caps')?
 
   fun val walk(handler: WalkHandler ref, follow_links: Bool = false) =>
     """

From 4781c41ca1d87fc3c1bd320c437a1f8df404e574 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 4 Aug 2021 18:38:56 -0500
Subject: [PATCH 02/26] Type changes in tests; rm partial ? denotations

---
 packages/files/_test.pony   | 38 ++++++++++-----------
 packages/process/_test.pony | 68 ++++++++++++++++++-------------------
 2 files changed, 52 insertions(+), 54 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 33f0a433ce..b4ab824ead 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -443,7 +443,7 @@ class iso _TestFileCreate is UnitTest
     try
       let path = "tmp.create"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -462,7 +462,7 @@ class iso _TestFileCreateExistsNotWriteable is _NonRootTest
     let content = "unwriteable"
     let path = "tmp.create-not-writeable"
     let ambient = h.env.root as AmbientAuth
-    let filepath = FilePath(FileAuth(ambient), path)?
+    let filepath = FilePath(FileAuth(ambient), path)
     try
       let mode: FileMode ref = FileMode.>private()
       mode.owner_read = true
@@ -569,7 +569,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       let file_path1 = FilePath(
         FileAuth(ambient),
         "tmp.create-missing-caps1",
-        consume no_create_caps)?
+        consume no_create_caps)
       let file1 = File(file_path1)
       h.assert_false(file1.valid())
       h.assert_is[FileErrNo](file1.errno(), FileError)
@@ -577,7 +577,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       let file_path2 = FilePath(
         FileAuth(ambient),
         "tmp.create-missing-caps2",
-        consume no_read_caps)?
+        consume no_read_caps)
       let file2 = File(file_path2)
       h.assert_false(file2.valid())
       h.assert_is[FileErrNo](file2.errno(), FileError)
@@ -585,7 +585,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       let file_path3 = FilePath(
         FileAuth(ambient),
         "tmp.create-missing-caps3",
-        consume no_write_caps)?
+        consume no_write_caps)
       let file3 = File(file_path3)
       h.assert_false(file3.valid())
       h.assert_is[FileErrNo](file3.errno(), FileError)
@@ -600,7 +600,7 @@ class iso _TestFileOpen is UnitTest
     try
       let path = "tmp.open"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -625,7 +625,7 @@ class iso _TestFileOpenError is UnitTest
     try
       let path = "tmp.openerror"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       h.assert_false(filepath.exists())
       let file = OpenFile(filepath)
       h.assert_true(file is FileError)
@@ -640,7 +640,7 @@ class _TestFileOpenWrite is UnitTest
     try
       let path = "tmp.open-write"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.print("write on file opened read-only")
       end
@@ -665,7 +665,7 @@ class iso _TestFileOpenPermissionDenied is _NonRootTest
         // with chmod there is no way to make a file not readable
       try
         let ambient = h.env.root as AmbientAuth
-        let filepath = FilePath(FileAuth(ambient), "tmp.open-not-readable")?
+        let filepath = FilePath(FileAuth(ambient), "tmp.open-not-readable")
         with file = CreateFile(filepath) as File do
           file.print("unreadable")
         end
@@ -695,7 +695,7 @@ class iso _TestFileLongLine is UnitTest
     try
       let path = "tmp.longline"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = File(filepath) do
         var longline = "foobar"
         for d in Range(0, 10) do
@@ -718,7 +718,7 @@ class iso _TestFileWrite is UnitTest
     try
       let path = "tmp.write"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.write("foobar\n")
       end
@@ -742,7 +742,7 @@ class iso _TestFileWritev is UnitTest
       wb.write(line2)
       let path = "tmp.writev"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -763,7 +763,7 @@ class iso _TestFileQueue is UnitTest
     try
       let path = "tmp.queue"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.queue("foobar\n")
       end
@@ -786,7 +786,7 @@ class iso _TestFileQueuev is UnitTest
       wb.write(line2)
       let path = "tmp.queuev"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.queuev(wb.done())
       end
@@ -820,7 +820,7 @@ class iso _TestFileMixedWriteQueue is UnitTest
       let queuev_data = wb.done()
       let path = "tmp.mixedwrite"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         file.print(line3)
         file.queue(line5)
@@ -862,7 +862,7 @@ class iso _TestFileWritevLarge is UnitTest
       end
       let path = "tmp.writevlarge"
       let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)?
+      let filepath = FilePath(FileAuth(ambient), path)
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -884,7 +884,7 @@ class iso _TestFileFlush is UnitTest
   fun apply(h: TestHelper) =>
     try
       let ambient = h.env.root as AmbientAuth
-      let path = FilePath(FileAuth(ambient), "tmp.flush")?
+      let path = FilePath(FileAuth(ambient), "tmp.flush")
       with file = CreateFile(path) as File do
         // Flush with no writes succeeds trivially, but does nothing.
         h.assert_true(file.flush())
@@ -912,7 +912,7 @@ class iso _TestFileReadMore is UnitTest
   fun name(): String => "files/File.read-more"
   fun apply(h: TestHelper)? =>
     let ambient = h.env.root as AmbientAuth
-    let path = FilePath(FileAuth(ambient), "tmp-read-more")?
+    let path = FilePath(FileAuth(ambient), "tmp-read-more")
     with file = CreateFile(path) as File do
       h.assert_true(file.write("foobar"))
     end
@@ -936,7 +936,7 @@ class iso _TestFileRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-file"
   fun apply(h: TestHelper) ? =>
     let ambient = h.env.root as AmbientAuth
-    let path = FilePath(FileAuth(ambient), "tmp-read-only")?
+    let path = FilePath(FileAuth(ambient), "tmp-read-only")
     try
       with file = CreateFile(path) as File do
         None
diff --git a/packages/process/_test.pony b/packages/process/_test.pony
index 8f53fbe372..cd98bc84bb 100644
--- a/packages/process/_test.pony
+++ b/packages/process/_test.pony
@@ -40,7 +40,7 @@ class _PathResolver
             break
               recover val
                 Iter[String]((consume paths).values())
-                  .map[FilePath]({(str_path)? => FilePath(auth, str_path)? })
+                  .map[FilePath]({(str_path) => FilePath(FileAuth(auth), str_path)})
                   .collect[Array[FilePath] ref](Array[FilePath](size))
               end
           end
@@ -129,16 +129,16 @@ class iso _TestFileExecCapabilityIsRequired is UnitTest
     let notifier: ProcessNotify iso = _ProcessClient(0, "", 1, h,
       ProcessError(CapError))
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
       let path =
         FilePath(
-          h.env.root as AmbientAuth,
+          FileAuth(auth),
           _CatCommand.path(path_resolver)?,
-          recover val FileCaps .> all() .> unset(FileExec) end)?
+          recover val FileCaps .> all() .> unset(FileExec) end)
       let args: Array[String] val = ["dontcare"]
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
-      let auth = h.env.root as AmbientAuth
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path, args, vars)
       h.dispose_when_done(pm)
@@ -160,7 +160,7 @@ class iso _TestNonExecutablePathResultsInExecveError is UnitTest
   fun apply(h: TestHelper) =>
     try
       let auth = h.env.root as AmbientAuth
-      let path = FilePath.mkdtemp(auth, "pony_execve_test")?
+      let path = FilePath.mkdtemp(FileAuth(auth), "pony_execve_test")?
       let args: Array[String] val = []
       let vars: Array[String] val = []
 
@@ -211,12 +211,12 @@ class iso _TestStdinStdout is UnitTest
     let size: USize = input.size() + ifdef windows then 2 else 0 end
     let notifier: ProcessNotify iso = _ProcessClient(size, "", 0, h)
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
-      let path = FilePath(h.env.root as AmbientAuth, _CatCommand.path(path_resolver)?)?
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
+      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
-      let auth = h.env.root as AmbientAuth
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path, args, vars)
       pm.write(input)
@@ -249,14 +249,15 @@ class iso _TestStderr is UnitTest
     let exit_code: I32 = ifdef windows then 0 else 1 end
     let notifier: ProcessNotify iso = _ProcessClient(0, errmsg, exit_code, h)
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
       let path = FilePath(
-        h.env.root as AmbientAuth,
+        FileAuth(auth),
         ifdef windows then
           "C:\\Windows\\System32\\cmd.exe"
         else
           _CatCommand.path(path_resolver)?
-        end)?
+        end)
       let args: Array[String] val = ifdef windows then
         ["cmd"; "/c"; "\"(echo message-to-stderr)1>&2\""]
       else
@@ -264,7 +265,6 @@ class iso _TestStderr is UnitTest
       end
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
-      let auth = h.env.root as AmbientAuth
       _pm  = ProcessMonitor(auth, auth, consume notifier, path, args, vars)
       if _pm isnt None then // write to STDIN of the child process
         let pm = _pm as ProcessMonitor
@@ -323,8 +323,9 @@ class iso _TestExpect is UnitTest
     end
 
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
-      let path = FilePath(h.env.root as AmbientAuth, _EchoPath(path_resolver)?)?
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
+      let path = FilePath(FileAuth(auth), _EchoPath(path_resolver)?)
       let args: Array[String] val = ifdef windows then
         ["cmd"; "/c"; "echo"; "hello carl"]
       else
@@ -332,7 +333,6 @@ class iso _TestExpect is UnitTest
       end
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
-      let auth = h.env.root as AmbientAuth
       let pm: ProcessMonitor = ProcessMonitor(auth, auth, consume notifier,
         path, args, vars)
       pm.done_writing()  // closing stdin allows "echo" to terminate
@@ -356,12 +356,12 @@ class iso _TestWritevOrdering is UnitTest
     let expected: USize = ifdef windows then 13 else 11 end
     let notifier: ProcessNotify iso = _ProcessClient(expected, "", 0, h)
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
-      let path = FilePath(h.env.root as AmbientAuth, _CatCommand.path(path_resolver)?)?
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
+      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
-      let auth = h.env.root as AmbientAuth
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path, args, vars)
       let params: Array[String] val = ["one"; "two"; "three"]
@@ -388,12 +388,12 @@ class iso _TestPrintvOrdering is UnitTest
     let expected: USize = ifdef windows then 17 else 14 end
     let notifier: ProcessNotify iso = _ProcessClient(expected, "", 0, h)
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
-      let path = FilePath(h.env.root as AmbientAuth, _CatCommand.path(path_resolver)?)?
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
+      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
-      let auth = h.env.root as AmbientAuth
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path, args, vars)
       let params: Array[String] val = ["one"; "two"; "three"]
@@ -430,13 +430,13 @@ class iso _TestStdinWriteBuf is UnitTest
 
     let notifier: ProcessNotify iso = _ProcessClient(out_size, "", 0, h)
     try
-      let path_resolver = _PathResolver(h.env.vars, h.env.root as AmbientAuth)
-      let path = FilePath(h.env.root as AmbientAuth, _CatCommand.path(path_resolver)?)?
+      let auth = h.env.root as AmbientAuth
+      let path_resolver = _PathResolver(h.env.vars, auth)
+      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
       // fork the child process and attach a ProcessMonitor
-      let auth = h.env.root as AmbientAuth
       _pm = ProcessMonitor(auth, auth, consume notifier, path, args, vars)
 
       if _pm isnt None then // write to STDIN of the child process
@@ -477,14 +477,13 @@ class _TestChdir is UnitTest
       + (ifdef windows then 2 else 1 end), "", 0, h)
     try
       let auth = h.env.root as AmbientAuth
-
-      let path = FilePath(auth, _PwdPath())?
+      let path = FilePath(FileAuth(auth), _PwdPath())
       let args: Array[String] val = _PwdArgs()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path,
-          args, vars, FilePath(auth, parent)?)
+          args, vars, FilePath(FileAuth(auth), parent))
       pm.done_writing()
       h.dispose_when_done(pm)
       h.long_test(30_000_000_000)
@@ -505,14 +504,13 @@ class _TestBadChdir is UnitTest
       _ProcessClient(0, "", _EXOSERR(), h, ProcessError(ChdirError))
     try
       let auth = h.env.root as AmbientAuth
-
-      let path = FilePath(auth, _PwdPath())?
+      let path = FilePath(FileAuth(auth), _PwdPath())
       let args: Array[String] val = _PwdArgs()
       let vars: Array[String] iso = recover Array[String](0) end
 
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path,
-          args, consume vars, FilePath(auth, badpath)?)
+          args, consume vars, FilePath(FileAuth(auth), badpath))
       pm.done_writing()
       h.dispose_when_done(pm)
       h.long_test(30_000_000_000)
@@ -541,9 +539,9 @@ class _TestBadExec is UnitTest
   fun ref set_up(h: TestHelper) ? =>
     let auth = h.env.root as AmbientAuth
     ifdef windows then
-      _bad_exec_path = FilePath(auth, "C:\\Windows\\system.ini")?
+      _bad_exec_path = FilePath(FileAuth(auth), "C:\\Windows\\system.ini")
     else
-      let tmp_dir = FilePath.mkdtemp(auth, "pony_stdlib_test_process_bad_exec")?
+      let tmp_dir = FilePath.mkdtemp(FileAuth(auth), "pony_stdlib_test_process_bad_exec")?
       _tmp_dir = tmp_dir
       let bad_exec_path = tmp_dir.join("_bad_exec.sh")?
       _bad_exec_path = bad_exec_path
@@ -603,7 +601,7 @@ class iso _TestLongRunningChild is UnitTest
 
     try
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(auth, _SleepCommand.path(path_resolver)?)?
+      let path = FilePath(FileAuth(auth), _SleepCommand.path(path_resolver)?)
       h.log(path.path)
       let args = _SleepCommand.args(where seconds = 2)
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
@@ -661,7 +659,7 @@ class iso _TestKillLongRunningChild is UnitTest
 
     try
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(auth, _SleepCommand.path(path_resolver)?)?
+      let path = FilePath(FileAuth(auth), _SleepCommand.path(path_resolver)?)
       h.log(path.path)
       let args = _SleepCommand.args(where seconds = 2)
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]

From 4f1ce12ce1ff3d04c4af921cbb4d91f5c76724af Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 4 Aug 2021 20:03:40 -0500
Subject: [PATCH 03/26] Update FilePath in examples

---
 examples/files/files.pony           | 3 ++-
 examples/mandelbrot/mandelbrot.pony | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/examples/files/files.pony b/examples/files/files.pony
index 3b2a8d145c..b12b8db468 100644
--- a/examples/files/files.pony
+++ b/examples/files/files.pony
@@ -5,8 +5,9 @@ actor Main
     let caps = recover val FileCaps.>set(FileRead).>set(FileStat) end
 
     try
+      let auth = env.root as AmbientAuth
       with file = OpenFile(
-        FilePath(env.root as AmbientAuth, env.args(1)?, caps)?) as File
+        FilePath(FileAuth(auth), env.args(1)?, caps)) as File
       do
         env.out.print(file.path.path)
         for line in file.lines() do
diff --git a/examples/mandelbrot/mandelbrot.pony b/examples/mandelbrot/mandelbrot.pony
index d2cc767964..375744d9a2 100644
--- a/examples/mandelbrot/mandelbrot.pony
+++ b/examples/mandelbrot/mandelbrot.pony
@@ -73,7 +73,7 @@ class val Config
   let outpath: (FilePath | None)
 
   new val create(env: Env) ? =>
-    let cs = CommandSpec.leaf("gups_opt",
+    let cs = CommandSpec.leaf("run",
       """
       The binary output can be converted to a PNG with the following command
       (ImageMagick Tools required):
@@ -114,7 +114,8 @@ class val Config
     width = cmd.option("width").i64().usize()
     outpath =
       try
-        FilePath(env.root as AmbientAuth, cmd.option("output").string())?
+        let auth = env.root as AmbientAuth
+        FilePath(FileAuth(auth), cmd.option("output").string())
       else
         None
       end

From cce778e3ee91746ecc5c15ae43f31fa4bd8ca6f4 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 4 Aug 2021 21:43:21 -0500
Subject: [PATCH 04/26] Fix additional space

---
 packages/files/file_path.pony | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index 000d9e2287..52e2ebda35 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -117,7 +117,7 @@ class val FilePath
     (let dir, let pre) = Path.split(prefix)
     let parent: FilePath = match base
       | let base': FileAuth => FilePath(base', dir)
-      | let base' : FilePath => FilePath.from(base', dir)?
+      | let base': FilePath => FilePath.from(base', dir)?
     end
 
     if not parent.mkdir() then

From 691b95831cb7e34b16aad99cf6af4d8ef93bd977 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Mon, 9 Aug 2021 20:08:17 -0500
Subject: [PATCH 05/26] Add FilePath.from no-error test

---
 packages/files/_test.pony | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index b4ab824ead..22a6fef092 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -31,6 +31,7 @@ actor Main is TestList
   ifdef not windows then
     test(_TestPathRoot)
   end
+    test(_TestFilePathFrom)
     test(_TestFileEOF)
     test(_TestFileOpenError)
     test(_TestFileCreate)
@@ -413,6 +414,19 @@ class iso _TestPathRoot is UnitTest
     h.assert_eq[String](res2, "/")
 
 
+class iso _TestFilePathFrom is UnitTest
+  fun name(): String => "files/FilePath.from"
+  fun apply(h: TestHelper) =>
+    try
+      let path = "tmp.filepath"
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)
+      h.assert_no_error({()? => FilePath.from(filepath, path)? })
+    else
+      h.fail("Unhandled error!")
+    end
+
+
 class iso _TestFileEOF is UnitTest
   fun name(): String => "files/File.eof-error"
   fun apply(h: TestHelper) =>

From 3e2374cf915f76758d1ef4f7cb6fb7057c4030a0 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Mon, 9 Aug 2021 20:09:48 -0500
Subject: [PATCH 06/26] Move FilePath.from test with other FilePath tests

---
 packages/files/_test.pony | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 22a6fef092..8f51a091d3 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -193,6 +193,20 @@ class iso _TestSymlink is UnitTest
       target_path.symlink(link_path),
       "could not create symbolic link to: " + target_path.path)
 
+
+class iso _TestFilePathFrom is UnitTest
+  fun name(): String => "files/FilePath.from"
+  fun apply(h: TestHelper) =>
+    try
+      let path = "tmp.filepath"
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)
+      h.assert_no_error({()? => FilePath.from(filepath, path)? })
+    else
+      h.fail("Unhandled error!")
+    end
+
+
 class iso _TestDirectoryOpen is UnitTest
   fun name(): String => "files/File.open.directory"
   fun apply(h: TestHelper) ? =>
@@ -414,19 +428,6 @@ class iso _TestPathRoot is UnitTest
     h.assert_eq[String](res2, "/")
 
 
-class iso _TestFilePathFrom is UnitTest
-  fun name(): String => "files/FilePath.from"
-  fun apply(h: TestHelper) =>
-    try
-      let path = "tmp.filepath"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
-      h.assert_no_error({()? => FilePath.from(filepath, path)? })
-    else
-      h.fail("Unhandled error!")
-    end
-
-
 class iso _TestFileEOF is UnitTest
   fun name(): String => "files/File.eof-error"
   fun apply(h: TestHelper) =>

From 7c373fbd72c0abedd0653e1ac31b6b25fecd57d8 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Mon, 9 Aug 2021 20:15:48 -0500
Subject: [PATCH 07/26] Add successful and failing FilePath.from tests

---
 packages/files/_test.pony | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 8f51a091d3..2388048d57 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -18,6 +18,8 @@ actor Main is TestList
     test(_TestSymlink)
   end
     test(_TestWalk)
+    test(_TestFilePathFrom)
+    test(_TestFilePathFromError)
     test(_TestDirectoryOpen)
     test(_TestDirectoryFileOpen)
     test(_TestPathClean)
@@ -31,7 +33,6 @@ actor Main is TestList
   ifdef not windows then
     test(_TestPathRoot)
   end
-    test(_TestFilePathFrom)
     test(_TestFileEOF)
     test(_TestFileOpenError)
     test(_TestFileCreate)
@@ -195,7 +196,7 @@ class iso _TestSymlink is UnitTest
 
 
 class iso _TestFilePathFrom is UnitTest
-  fun name(): String => "files/FilePath.from"
+  fun name(): String => "files/FilePath.from-success"
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.filepath"
@@ -206,6 +207,18 @@ class iso _TestFilePathFrom is UnitTest
       h.fail("Unhandled error!")
     end
 
+class iso _TestFilePathFromError is UnitTest
+  fun name(): String => "files/FilePath.from-error"
+  fun apply(h: TestHelper) =>
+    try
+      let path = "tmp.filepath"
+      let ambient = h.env.root as AmbientAuth
+      let filepath = FilePath(FileAuth(ambient), path)
+      h.assert_error({()? => FilePath.from(filepath, "/")? })
+    else
+      h.fail("Unhandled error!")
+    end
+
 
 class iso _TestDirectoryOpen is UnitTest
   fun name(): String => "files/File.open.directory"

From 37eaa2d75dfab24571b12ac0dc8e5c34951673dd Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Tue, 10 Aug 2021 17:20:41 -0500
Subject: [PATCH 08/26] Add release notes

---
 .release-notes/split-filepath.md | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 .release-notes/split-filepath.md

diff --git a/.release-notes/split-filepath.md b/.release-notes/split-filepath.md
new file mode 100644
index 0000000000..fc7e7b2b52
--- /dev/null
+++ b/.release-notes/split-filepath.md
@@ -0,0 +1,3 @@
+## Split `FilePath` construction into two methods
+
+`FilePath` previously had only one constructor, the default `create`, which used a union of `(AmbientAuth | FilePath)`. The first half of this union `AmbientAuth` could never `error`, while the second `FilePath` could `error`. By splitting construction into two methods, we now have a default `create` which cannot `error` -- now using a "files" package root authority `FileAuth` rather than global root authority `AmbientAuth` -- as well as a new `from` constructor using `FilePath`.

From e10275403aebe8a830462085e8e21acd06e54a07 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:27:18 -0500
Subject: [PATCH 09/26] Update release notes

---
 .release-notes/split-filepath.md | 50 +++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/.release-notes/split-filepath.md b/.release-notes/split-filepath.md
index fc7e7b2b52..d57ed6290e 100644
--- a/.release-notes/split-filepath.md
+++ b/.release-notes/split-filepath.md
@@ -1,3 +1,51 @@
 ## Split `FilePath` construction into two methods
 
-`FilePath` previously had only one constructor, the default `create`, which used a union of `(AmbientAuth | FilePath)`. The first half of this union `AmbientAuth` could never `error`, while the second `FilePath` could `error`. By splitting construction into two methods, we now have a default `create` which cannot `error` -- now using a "files" package root authority `FileAuth` rather than global root authority `AmbientAuth` -- as well as a new `from` constructor using `FilePath`.
+`FilePath` previously had only one constructor, the default `create`, which used a union of `(AmbientAuth | FilePath)`. The first half of this union `AmbientAuth` could never `error`, while the second `FilePath` could `error`. By splitting construction into two methods, we now have a default `create` constructor which cannot `error` and a new `from` constructor which can `error`. The default `create` constructor uses a new "files" package root authority `FileAuth` rather than global root authority `AmbientAuth`, while the new `from` constructor uses `FilePath`.
+
+The result of this change is that three user changes are needed, namely around `create`, `from`, and `mkdtemp`.
+
+Before `create` using `AmbientAuth` to now `create` using `FileAuth`:
+
+```pony
+let ambient: AmbientAuth = ...
+let filepath: FilePath = FilePath(ambient, path)?
+```
+
+becomes
+
+```pony
+let ambient: AmbientAuth = ...
+let filepath: FilePath = FilePath(FileAuth(ambient), path)
+```
+
+---
+
+Before `create` using `FilePath` to now `from` using `FilePath`:
+
+```pony
+let filepath: FilePath = ...
+let subpath = FilePath(filepath, path)?
+```
+
+becomes
+
+```pony
+let filepath: FilePath = ...
+let subpath = FilePath.from(filepath, path)?
+```
+
+---
+
+Before `mkdtemp` using `AmbientAuth` to now `mkdtemp` using `FileAuth`:
+
+```pony
+let ambient: AmbientAuth = ...
+let tempdir = FilePath.mkdtemp(ambient, prefix)?
+```
+
+becomes
+
+```pony
+let ambient: AmbientAuth = ...
+let tempdir = FilePath.mkdtemp(FileAuth(ambient), prefix)?
+```

From 3f7a007547cf159fa3e8c37b4506809093b9d6fb Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:29:14 -0500
Subject: [PATCH 10/26] Add newline

---
 packages/files/auth.pony | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/files/auth.pony b/packages/files/auth.pony
index d7f57c3107..35cb63af3d 100644
--- a/packages/files/auth.pony
+++ b/packages/files/auth.pony
@@ -1,3 +1,3 @@
 primitive FileAuth
   new create(from: AmbientAuth) =>
-    None
\ No newline at end of file
+    None

From 5c284098b53022abd759972d9fb8a290849cd5ee Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:32:27 -0500
Subject: [PATCH 11/26] Shorten construction to one line

---
 examples/mandelbrot/mandelbrot.pony | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/examples/mandelbrot/mandelbrot.pony b/examples/mandelbrot/mandelbrot.pony
index 375744d9a2..c8ef7273d0 100644
--- a/examples/mandelbrot/mandelbrot.pony
+++ b/examples/mandelbrot/mandelbrot.pony
@@ -114,8 +114,7 @@ class val Config
     width = cmd.option("width").i64().usize()
     outpath =
       try
-        let auth = env.root as AmbientAuth
-        FilePath(FileAuth(auth), cmd.option("output").string())
+        FilePath(FileAuth(env.root as AmbientAuth), cmd.option("output").string())
       else
         None
       end

From 7fd83be2daa88282f6695e6b368bbe3bd85cb947 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:39:04 -0500
Subject: [PATCH 12/26] Add docstring explaining error

---
 packages/files/_test.pony | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 2388048d57..f4858fb4fd 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -196,6 +196,13 @@ class iso _TestSymlink is UnitTest
 
 
 class iso _TestFilePathFrom is UnitTest
+  """
+  _TestFilePathFrom checks that it is error-free to produce a filepath
+  using the from constructor to the same path of the provided `FilePath`.
+
+  That is, a FilePath to some user file/directory can then be used to produce
+  a FilePath to the same file/directory.
+  """
   fun name(): String => "files/FilePath.from-success"
   fun apply(h: TestHelper) =>
     try
@@ -208,6 +215,13 @@ class iso _TestFilePathFrom is UnitTest
     end
 
 class iso _TestFilePathFromError is UnitTest
+  """
+  _TestFilePathFromError checks that it is an error to produce a filepath
+  using the from constructor which is not a subpath of the provided `FilePath`.
+
+  That is, a FilePath to some user file/directory cannot be used to create a FilePath to
+  the root directory.
+  """
   fun name(): String => "files/FilePath.from-error"
   fun apply(h: TestHelper) =>
     try

From 33f7700766c6c0bfeb479a2d55e898a8ae3dafc6 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:42:29 -0500
Subject: [PATCH 13/26] Informative error message

---
 packages/files/_test.pony | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index f4858fb4fd..559e1fd9ff 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -211,7 +211,7 @@ class iso _TestFilePathFrom is UnitTest
       let filepath = FilePath(FileAuth(ambient), path)
       h.assert_no_error({()? => FilePath.from(filepath, path)? })
     else
-      h.fail("Unhandled error!")
+      h.fail("Could not build a path to the same file/directory.")
     end
 
 class iso _TestFilePathFromError is UnitTest
@@ -230,7 +230,7 @@ class iso _TestFilePathFromError is UnitTest
       let filepath = FilePath(FileAuth(ambient), path)
       h.assert_error({()? => FilePath.from(filepath, "/")? })
     else
-      h.fail("Unhandled error!")
+      h.fail("Could build a path from a subdirectory to a parent directory.")
     end
 
 

From bf02ca86c5668f5494f6954f9f1601b998e376a2 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:55:34 -0500
Subject: [PATCH 14/26] Use match to remove try-block

---
 packages/files/_test.pony | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 559e1fd9ff..17b21d6a49 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -194,7 +194,6 @@ class iso _TestSymlink is UnitTest
       target_path.symlink(link_path),
       "could not create symbolic link to: " + target_path.path)
 
-
 class iso _TestFilePathFrom is UnitTest
   """
   _TestFilePathFrom checks that it is error-free to produce a filepath
@@ -205,13 +204,13 @@ class iso _TestFilePathFrom is UnitTest
   """
   fun name(): String => "files/FilePath.from-success"
   fun apply(h: TestHelper) =>
-    try
+    match h.env.root
+    | let auth: AmbientAuth =>
       let path = "tmp.filepath"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(auth), path)
       h.assert_no_error({()? => FilePath.from(filepath, path)? })
     else
-      h.fail("Could not build a path to the same file/directory.")
+      h.fail("env.root isn't AmbientAuth.")
     end
 
 class iso _TestFilePathFromError is UnitTest
@@ -224,13 +223,13 @@ class iso _TestFilePathFromError is UnitTest
   """
   fun name(): String => "files/FilePath.from-error"
   fun apply(h: TestHelper) =>
-    try
+    match h.env.root
+    | let auth: AmbientAuth =>
       let path = "tmp.filepath"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(auth), path)
       h.assert_error({()? => FilePath.from(filepath, "/")? })
     else
-      h.fail("Could build a path from a subdirectory to a parent directory.")
+      h.fail("env.root isn't AmbientAuth.")
     end
 
 

From 647f97f81cf10f4753520cea45fa03f696324d0c Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:55:54 -0500
Subject: [PATCH 15/26] One space between unit tests

---
 packages/files/_test.pony | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 17b21d6a49..1a719a862d 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -109,7 +109,6 @@ trait iso _NonRootTest is UnitTest
       end
     end
 
-
 class iso _TestMkdtemp is UnitTest
   fun name(): String => "files/FilePath.mkdtemp"
   fun apply(h: TestHelper) ? =>
@@ -121,7 +120,6 @@ class iso _TestMkdtemp is UnitTest
       h.assert_true(tmp.remove())
     end
 
-
 class iso _TestWalk is UnitTest
   fun name(): String => "files/FilePath.walk"
   fun apply(h: TestHelper) ? =>
@@ -232,7 +230,6 @@ class iso _TestFilePathFromError is UnitTest
       h.fail("env.root isn't AmbientAuth.")
     end
 
-
 class iso _TestDirectoryOpen is UnitTest
   fun name(): String => "files/File.open.directory"
   fun apply(h: TestHelper) ? =>
@@ -308,7 +305,6 @@ class iso _TestPathClean is UnitTest
       h.assert_eq[String](res7, "/foo/qux")
     end
 
-
 class iso _TestPathJoin is UnitTest
   fun name(): String => "files/Path.join"
   fun apply(h: TestHelper) =>
@@ -331,14 +327,12 @@ class iso _TestPathJoin is UnitTest
       h.assert_eq[String](res3, "/foo/dir/base.ext")
     end
 
-
 class iso _TestPathRel is UnitTest
   fun name(): String => "files/Path.rel"
   fun apply(h: TestHelper) ? =>
     let res = Path.rel("foo/bar", "foo/bar/baz")?
     h.assert_eq[String](res, "baz")
 
-
 class iso _TestPathSplit is UnitTest
   fun name(): String => "files/Path.split"
   fun apply(h: TestHelper) =>
@@ -377,7 +371,6 @@ class iso _TestPathSplit is UnitTest
       end
     end
 
-
 class iso _TestPathDir is UnitTest
   fun name(): String => "files/Path.dir"
   fun apply(h: TestHelper) =>
@@ -395,7 +388,6 @@ class iso _TestPathDir is UnitTest
       h.assert_eq[String](res2, "/foo/bar/dir")
     end
 
-
 class iso _TestPathBase is UnitTest
   fun name(): String => "files/Path.dir"
   fun apply(h: TestHelper) =>
@@ -410,7 +402,6 @@ class iso _TestPathBase is UnitTest
     h.assert_eq[String](Path.base(p1, false), "base")
     h.assert_eq[String](Path.base(p2), "")
 
-
 class iso _TestPathExt is UnitTest
   fun name(): String => "files/Path.ext"
   fun apply(h: TestHelper) =>
@@ -429,7 +420,6 @@ class iso _TestPathExt is UnitTest
       h.assert_eq[String](res2, "")
     end
 
-
 class iso _TestPathVolume is UnitTest
   fun name(): String => "files/Path.volume"
   fun apply(h: TestHelper) =>
@@ -444,7 +434,6 @@ class iso _TestPathVolume is UnitTest
       h.assert_eq[String](res2, "")
     end
 
-
 class iso _TestPathRoot is UnitTest
   fun name(): String => "files/Path.root"
   fun apply(h: TestHelper) =>
@@ -453,7 +442,6 @@ class iso _TestPathRoot is UnitTest
     h.assert_eq[String](res1, "/")
     h.assert_eq[String](res2, "/")
 
-
 class iso _TestFileEOF is UnitTest
   fun name(): String => "files/File.eof-error"
   fun apply(h: TestHelper) =>
@@ -477,7 +465,6 @@ class iso _TestFileEOF is UnitTest
       h.fail("Unhandled error!")
     end
 
-
 class iso _TestFileCreate is UnitTest
   fun name(): String => "files/File.create"
   fun apply(h: TestHelper) =>
@@ -496,7 +483,6 @@ class iso _TestFileCreate is UnitTest
       h.fail("Unhandled error!")
     end
 
-
 class iso _TestFileCreateExistsNotWriteable is _NonRootTest
   fun name(): String => "files/File.create-exists-not-writeable"
   fun apply_as_non_root(h: TestHelper) ? =>
@@ -529,7 +515,6 @@ class iso _TestFileCreateExistsNotWriteable is _NonRootTest
       h.assert_true(filepath.remove())
     end
 
-
 class iso _TestFileCreateDirNotWriteable is _NonRootTest
   fun name(): String => "files/File.create-dir-not-writeable"
   fun apply_as_non_root(h: TestHelper) =>
@@ -659,7 +644,6 @@ class iso _TestFileOpen is UnitTest
       h.fail("Unhandled error!")
     end
 
-
 class iso _TestFileOpenError is UnitTest
   fun name(): String => "files/File.open-error"
   fun apply(h: TestHelper) =>
@@ -674,7 +658,6 @@ class iso _TestFileOpenError is UnitTest
       h.fail("Unhandled error!")
     end
 
-
 class _TestFileOpenWrite is UnitTest
   fun name(): String => "files/File.open.write"
   fun apply(h: TestHelper) =>
@@ -697,7 +680,6 @@ class _TestFileOpenWrite is UnitTest
       h.fail("Unhandled error!")
     end
 
-
 class iso _TestFileOpenPermissionDenied is _NonRootTest
   fun name(): String => "files/File.open-permission-denied"
   fun apply_as_non_root(h: TestHelper) =>
@@ -729,7 +711,6 @@ class iso _TestFileOpenPermissionDenied is _NonRootTest
       end
     end
 
-
 class iso _TestFileLongLine is UnitTest
   fun name(): String => "files/File.longline"
   fun apply(h: TestHelper) =>

From 306e95847ff5ec9694122514372b2757db3af185 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 19:58:44 -0500
Subject: [PATCH 16/26] ? at end of constructor, no newline

---
 packages/files/file_path.pony | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index 52e2ebda35..e743770c41 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -71,8 +71,7 @@ class val FilePath
   new val from(
     base: FilePath,
     path': String,
-    caps': FileCaps val = recover val FileCaps .> all() end)
-    ?
+    caps': FileCaps val = recover val FileCaps .> all() end) ?
   =>
     """
     Create a new path from an existing `FilePath`.
@@ -99,8 +98,7 @@ class val FilePath
   new val mkdtemp(
     base: (FilePath | FileAuth),
     prefix: String = "",
-    caps': FileCaps val = recover val FileCaps .> all() end)
-    ?
+    caps': FileCaps val = recover val FileCaps .> all() end) ?
   =>
     """
     Create a temporary directory and returns a path to it. The directory's name

From 651663f1ab8f3b4c6b2a67e6e2d0be1f04a0ad28 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 18 Aug 2021 20:08:00 -0500
Subject: [PATCH 17/26] Remove tmp ambient variables, single line construction

---
 packages/files/_test.pony | 94 +++++++++++++--------------------------
 1 file changed, 32 insertions(+), 62 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 1a719a862d..83c2302cb8 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -63,8 +63,7 @@ actor Main is TestList
 
 primitive _FileHelper
   fun make_files(h: TestHelper, files: Array[String]): FilePath ? =>
-    let ambient = h.env.root as AmbientAuth
-    let top = Directory(FilePath.mkdtemp(FileAuth(ambient),
+    let top = Directory(FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth),
       "tmp._FileHelper.")?)?
     for f in files.values() do
       try
@@ -112,8 +111,7 @@ trait iso _NonRootTest is UnitTest
 class iso _TestMkdtemp is UnitTest
   fun name(): String => "files/FilePath.mkdtemp"
   fun apply(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    let tmp = FilePath.mkdtemp(FileAuth(ambient), "tmp.TestMkdtemp.")?
+    let tmp = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "tmp.TestMkdtemp.")?
     try
       h.assert_true(FileInfo(tmp)?.directory)
     then
@@ -149,8 +147,7 @@ class iso _TestSymlink is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "symlink")?
+    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "symlink")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -233,8 +230,7 @@ class iso _TestFilePathFromError is UnitTest
 class iso _TestDirectoryOpen is UnitTest
   fun name(): String => "files/File.open.directory"
   fun apply(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    let tmp = FilePath.mkdtemp(FileAuth(ambient), "tmp.TestDiropen.")?
+    let tmp = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "tmp.TestDiropen.")?
 
     try
       h.assert_true(FileInfo(tmp)?.directory)
@@ -250,10 +246,9 @@ class iso _TestDirectoryFileOpen is UnitTest
   fun name(): String => "files/Directory.open-file"
   fun apply(h: TestHelper) =>
   try
-    let ambient = h.env.root as AmbientAuth
     // make a temporary directory
     let dir_path = FilePath.mkdtemp(
-      FileAuth(ambient),
+      FileAuth(h.env.root as AmbientAuth),
       "tmp.directory.open-file")?
     try
       let dir = Directory(dir_path)?
@@ -447,8 +442,7 @@ class iso _TestFileEOF is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.eof"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = File(filepath) do
         file.write("foobar")
         file.sync()
@@ -470,8 +464,7 @@ class iso _TestFileCreate is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.create"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -488,8 +481,7 @@ class iso _TestFileCreateExistsNotWriteable is _NonRootTest
   fun apply_as_non_root(h: TestHelper) ? =>
     let content = "unwriteable"
     let path = "tmp.create-not-writeable"
-    let ambient = h.env.root as AmbientAuth
-    let filepath = FilePath(FileAuth(ambient), path)
+    let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
     try
       let mode: FileMode ref = FileMode.>private()
       mode.owner_read = true
@@ -520,10 +512,9 @@ class iso _TestFileCreateDirNotWriteable is _NonRootTest
   fun apply_as_non_root(h: TestHelper) =>
     ifdef not windows then
       try
-        let ambient = h.env.root as AmbientAuth
         let dir_path =
           FilePath.mkdtemp(
-            FileAuth(ambient),
+            FileAuth(h.env.root as AmbientAuth),
             "tmp.create-dir-not-writeable")?
         let mode: FileMode ref = FileMode.>private()
         mode.owner_read = true
@@ -554,10 +545,9 @@ class iso _TestFileOpenInDirNotWriteable is UnitTest
   fun apply(h: TestHelper) =>
     ifdef not windows then
       try
-        let ambient = h.env.root as AmbientAuth
         // make a temporary directory
         let dir_path = FilePath.mkdtemp(
-          FileAuth(ambient),
+          FileAuth(h.env.root as AmbientAuth),
           "tmp.open-dir-not-writeable")?
         try
           let dir = Directory(dir_path)?
@@ -591,9 +581,8 @@ class iso _TestFileCreateMissingCaps is UnitTest
       let no_read_caps = FileCaps.>all().>unset(FileWrite)
       let no_write_caps = FileCaps.>all().>unset(FileRead)
 
-      let ambient = h.env.root as AmbientAuth
       let file_path1 = FilePath(
-        FileAuth(ambient),
+        FileAuth(h.env.root as AmbientAuth),
         "tmp.create-missing-caps1",
         consume no_create_caps)
       let file1 = File(file_path1)
@@ -601,7 +590,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       h.assert_is[FileErrNo](file1.errno(), FileError)
 
       let file_path2 = FilePath(
-        FileAuth(ambient),
+        FileAuth(h.env.root as AmbientAuth),
         "tmp.create-missing-caps2",
         consume no_read_caps)
       let file2 = File(file_path2)
@@ -609,7 +598,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       h.assert_is[FileErrNo](file2.errno(), FileError)
 
       let file_path3 = FilePath(
-        FileAuth(ambient),
+        FileAuth(h.env.root as AmbientAuth),
         "tmp.create-missing-caps3",
         consume no_write_caps)
       let file3 = File(file_path3)
@@ -625,8 +614,7 @@ class iso _TestFileOpen is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.open"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -649,8 +637,7 @@ class iso _TestFileOpenError is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.openerror"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       h.assert_false(filepath.exists())
       let file = OpenFile(filepath)
       h.assert_true(file is FileError)
@@ -663,8 +650,7 @@ class _TestFileOpenWrite is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.open-write"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.print("write on file opened read-only")
       end
@@ -687,8 +673,7 @@ class iso _TestFileOpenPermissionDenied is _NonRootTest
         // on windows all files are always writeable
         // with chmod there is no way to make a file not readable
       try
-        let ambient = h.env.root as AmbientAuth
-        let filepath = FilePath(FileAuth(ambient), "tmp.open-not-readable")
+        let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp.open-not-readable")
         with file = CreateFile(filepath) as File do
           file.print("unreadable")
         end
@@ -716,8 +701,7 @@ class iso _TestFileLongLine is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.longline"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = File(filepath) do
         var longline = "foobar"
         for d in Range(0, 10) do
@@ -739,8 +723,7 @@ class iso _TestFileWrite is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.write"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.write("foobar\n")
       end
@@ -763,8 +746,7 @@ class iso _TestFileWritev is UnitTest
       wb.write(line1)
       wb.write(line2)
       let path = "tmp.writev"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -784,8 +766,7 @@ class iso _TestFileQueue is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.queue"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.queue("foobar\n")
       end
@@ -807,8 +788,7 @@ class iso _TestFileQueuev is UnitTest
       wb.write(line1)
       wb.write(line2)
       let path = "tmp.queuev"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.queuev(wb.done())
       end
@@ -841,8 +821,7 @@ class iso _TestFileMixedWriteQueue is UnitTest
       wb.write(line6)
       let queuev_data = wb.done()
       let path = "tmp.mixedwrite"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         file.print(line3)
         file.queue(line5)
@@ -883,8 +862,7 @@ class iso _TestFileWritevLarge is UnitTest
         count = count + 1
       end
       let path = "tmp.writevlarge"
-      let ambient = h.env.root as AmbientAuth
-      let filepath = FilePath(FileAuth(ambient), path)
+      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -905,8 +883,7 @@ class iso _TestFileFlush is UnitTest
   fun name(): String => "files/File.flush"
   fun apply(h: TestHelper) =>
     try
-      let ambient = h.env.root as AmbientAuth
-      let path = FilePath(FileAuth(ambient), "tmp.flush")
+      let path = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp.flush")
       with file = CreateFile(path) as File do
         // Flush with no writes succeeds trivially, but does nothing.
         h.assert_true(file.flush())
@@ -933,8 +910,7 @@ class iso _TestFileFlush is UnitTest
 class iso _TestFileReadMore is UnitTest
   fun name(): String => "files/File.read-more"
   fun apply(h: TestHelper)? =>
-    let ambient = h.env.root as AmbientAuth
-    let path = FilePath(FileAuth(ambient), "tmp-read-more")
+    let path = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp-read-more")
     with file = CreateFile(path) as File do
       h.assert_true(file.write("foobar"))
     end
@@ -957,8 +933,7 @@ class iso _TestFileReadMore is UnitTest
 class iso _TestFileRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-file"
   fun apply(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    let path = FilePath(FileAuth(ambient), "tmp-read-only")
+    let path = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp-read-only")
     try
       with file = CreateFile(path) as File do
         None
@@ -980,8 +955,7 @@ class iso _TestDirectoryRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-directory"
 
   fun apply(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    let path = FilePath.mkdtemp(FileAuth(ambient), "tmp-read-only-dir")?
+    let path = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "tmp-read-only-dir")?
     let dir = Directory(path)?
     try
       let mode: FileMode ref = FileMode
@@ -1003,8 +977,7 @@ class iso _TestFileLinesEmptyFile is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "empty")?
+    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "empty")?
 
   fun ref tear_down(h: TestHelper) =>
     try (tmp_dir as FilePath).remove() end
@@ -1050,8 +1023,7 @@ class iso _TestFileLinesSingleLine is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "single-line")?
+    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "single-line")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -1118,8 +1090,7 @@ class _TestFileLinesMultiLine is UnitTest
   ]
 
   fun ref set_up(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "multi-line")?
+    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "multi-line")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -1164,8 +1135,7 @@ class _TestFileLinesMovingCursor is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    let ambient = h.env.root as AmbientAuth
-    tmp_dir = FilePath.mkdtemp(FileAuth(ambient), "moving-cursor")?
+    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "moving-cursor")?
 
   fun ref tear_down(h: TestHelper) =>
     try

From 7bc764037525dae7b078ebaed8864b741e1ba706 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Sat, 28 Aug 2021 20:59:39 -0500
Subject: [PATCH 18/26] FileAuth.create uses union of AmbientAuth and FileAuth

---
 packages/files/_test.pony     | 85 +++++++++++++++++++++--------------
 packages/files/file_path.pony |  5 ++-
 2 files changed, 54 insertions(+), 36 deletions(-)

diff --git a/packages/files/_test.pony b/packages/files/_test.pony
index 83c2302cb8..6683ed9011 100644
--- a/packages/files/_test.pony
+++ b/packages/files/_test.pony
@@ -18,6 +18,7 @@ actor Main is TestList
     test(_TestSymlink)
   end
     test(_TestWalk)
+    test(_TestFilePathFileAuth)
     test(_TestFilePathFrom)
     test(_TestFilePathFromError)
     test(_TestDirectoryOpen)
@@ -63,7 +64,7 @@ actor Main is TestList
 
 primitive _FileHelper
   fun make_files(h: TestHelper, files: Array[String]): FilePath ? =>
-    let top = Directory(FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth),
+    let top = Directory(FilePath.mkdtemp(h.env.root as AmbientAuth,
       "tmp._FileHelper.")?)?
     for f in files.values() do
       try
@@ -111,7 +112,7 @@ trait iso _NonRootTest is UnitTest
 class iso _TestMkdtemp is UnitTest
   fun name(): String => "files/FilePath.mkdtemp"
   fun apply(h: TestHelper) ? =>
-    let tmp = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "tmp.TestMkdtemp.")?
+    let tmp = FilePath.mkdtemp(h.env.root as AmbientAuth, "tmp.TestMkdtemp.")?
     try
       h.assert_true(FileInfo(tmp)?.directory)
     then
@@ -147,7 +148,7 @@ class iso _TestSymlink is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "symlink")?
+    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "symlink")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -189,6 +190,22 @@ class iso _TestSymlink is UnitTest
       target_path.symlink(link_path),
       "could not create symbolic link to: " + target_path.path)
 
+class iso _TestFilePathFileAuth is UnitTest
+  """
+  _TestFilePathFileAuth checks that it is error-free to produce a filepath
+  using `FileAuth` created from `AmbientAuth`.
+  """
+  fun name(): String => "files/FilePath.create-w-fileauth"
+  fun apply(h: TestHelper) =>
+    match h.env.root
+    | let auth: AmbientAuth =>
+      let path = "tmp.filepath"
+      let filepath = FilePath(FileAuth(auth), path)
+      h.assert_no_error({()? => FilePath.from(filepath, path)? })
+    else
+      h.fail("env.root isn't AmbientAuth.")
+    end
+
 class iso _TestFilePathFrom is UnitTest
   """
   _TestFilePathFrom checks that it is error-free to produce a filepath
@@ -202,7 +219,7 @@ class iso _TestFilePathFrom is UnitTest
     match h.env.root
     | let auth: AmbientAuth =>
       let path = "tmp.filepath"
-      let filepath = FilePath(FileAuth(auth), path)
+      let filepath = FilePath(auth, path)
       h.assert_no_error({()? => FilePath.from(filepath, path)? })
     else
       h.fail("env.root isn't AmbientAuth.")
@@ -221,7 +238,7 @@ class iso _TestFilePathFromError is UnitTest
     match h.env.root
     | let auth: AmbientAuth =>
       let path = "tmp.filepath"
-      let filepath = FilePath(FileAuth(auth), path)
+      let filepath = FilePath(auth, path)
       h.assert_error({()? => FilePath.from(filepath, "/")? })
     else
       h.fail("env.root isn't AmbientAuth.")
@@ -230,7 +247,7 @@ class iso _TestFilePathFromError is UnitTest
 class iso _TestDirectoryOpen is UnitTest
   fun name(): String => "files/File.open.directory"
   fun apply(h: TestHelper) ? =>
-    let tmp = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "tmp.TestDiropen.")?
+    let tmp = FilePath.mkdtemp(h.env.root as AmbientAuth, "tmp.TestDiropen.")?
 
     try
       h.assert_true(FileInfo(tmp)?.directory)
@@ -248,7 +265,7 @@ class iso _TestDirectoryFileOpen is UnitTest
   try
     // make a temporary directory
     let dir_path = FilePath.mkdtemp(
-      FileAuth(h.env.root as AmbientAuth),
+      h.env.root as AmbientAuth,
       "tmp.directory.open-file")?
     try
       let dir = Directory(dir_path)?
@@ -442,7 +459,7 @@ class iso _TestFileEOF is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.eof"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = File(filepath) do
         file.write("foobar")
         file.sync()
@@ -464,7 +481,7 @@ class iso _TestFileCreate is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.create"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -481,7 +498,7 @@ class iso _TestFileCreateExistsNotWriteable is _NonRootTest
   fun apply_as_non_root(h: TestHelper) ? =>
     let content = "unwriteable"
     let path = "tmp.create-not-writeable"
-    let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+    let filepath = FilePath(h.env.root as AmbientAuth, path)
     try
       let mode: FileMode ref = FileMode.>private()
       mode.owner_read = true
@@ -514,7 +531,7 @@ class iso _TestFileCreateDirNotWriteable is _NonRootTest
       try
         let dir_path =
           FilePath.mkdtemp(
-            FileAuth(h.env.root as AmbientAuth),
+            h.env.root as AmbientAuth,
             "tmp.create-dir-not-writeable")?
         let mode: FileMode ref = FileMode.>private()
         mode.owner_read = true
@@ -547,7 +564,7 @@ class iso _TestFileOpenInDirNotWriteable is UnitTest
       try
         // make a temporary directory
         let dir_path = FilePath.mkdtemp(
-          FileAuth(h.env.root as AmbientAuth),
+          h.env.root as AmbientAuth,
           "tmp.open-dir-not-writeable")?
         try
           let dir = Directory(dir_path)?
@@ -582,7 +599,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       let no_write_caps = FileCaps.>all().>unset(FileRead)
 
       let file_path1 = FilePath(
-        FileAuth(h.env.root as AmbientAuth),
+        h.env.root as AmbientAuth,
         "tmp.create-missing-caps1",
         consume no_create_caps)
       let file1 = File(file_path1)
@@ -590,7 +607,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       h.assert_is[FileErrNo](file1.errno(), FileError)
 
       let file_path2 = FilePath(
-        FileAuth(h.env.root as AmbientAuth),
+        h.env.root as AmbientAuth,
         "tmp.create-missing-caps2",
         consume no_read_caps)
       let file2 = File(file_path2)
@@ -598,7 +615,7 @@ class iso _TestFileCreateMissingCaps is UnitTest
       h.assert_is[FileErrNo](file2.errno(), FileError)
 
       let file_path3 = FilePath(
-        FileAuth(h.env.root as AmbientAuth),
+        h.env.root as AmbientAuth,
         "tmp.create-missing-caps3",
         consume no_write_caps)
       let file3 = File(file_path3)
@@ -614,7 +631,7 @@ class iso _TestFileOpen is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.open"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.print("foobar")
       end
@@ -637,7 +654,7 @@ class iso _TestFileOpenError is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.openerror"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       h.assert_false(filepath.exists())
       let file = OpenFile(filepath)
       h.assert_true(file is FileError)
@@ -650,7 +667,7 @@ class _TestFileOpenWrite is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.open-write"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.print("write on file opened read-only")
       end
@@ -673,7 +690,7 @@ class iso _TestFileOpenPermissionDenied is _NonRootTest
         // on windows all files are always writeable
         // with chmod there is no way to make a file not readable
       try
-        let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp.open-not-readable")
+        let filepath = FilePath(h.env.root as AmbientAuth, "tmp.open-not-readable")
         with file = CreateFile(filepath) as File do
           file.print("unreadable")
         end
@@ -701,7 +718,7 @@ class iso _TestFileLongLine is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.longline"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = File(filepath) do
         var longline = "foobar"
         for d in Range(0, 10) do
@@ -723,7 +740,7 @@ class iso _TestFileWrite is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.write"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.write("foobar\n")
       end
@@ -746,7 +763,7 @@ class iso _TestFileWritev is UnitTest
       wb.write(line1)
       wb.write(line2)
       let path = "tmp.writev"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -766,7 +783,7 @@ class iso _TestFileQueue is UnitTest
   fun apply(h: TestHelper) =>
     try
       let path = "tmp.queue"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.queue("foobar\n")
       end
@@ -788,7 +805,7 @@ class iso _TestFileQueuev is UnitTest
       wb.write(line1)
       wb.write(line2)
       let path = "tmp.queuev"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.queuev(wb.done())
       end
@@ -821,7 +838,7 @@ class iso _TestFileMixedWriteQueue is UnitTest
       wb.write(line6)
       let queuev_data = wb.done()
       let path = "tmp.mixedwrite"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         file.print(line3)
         file.queue(line5)
@@ -862,7 +879,7 @@ class iso _TestFileWritevLarge is UnitTest
         count = count + 1
       end
       let path = "tmp.writevlarge"
-      let filepath = FilePath(FileAuth(h.env.root as AmbientAuth), path)
+      let filepath = FilePath(h.env.root as AmbientAuth, path)
       with file = CreateFile(filepath) as File do
         h.assert_true(file.writev(wb.done()))
       end
@@ -883,7 +900,7 @@ class iso _TestFileFlush is UnitTest
   fun name(): String => "files/File.flush"
   fun apply(h: TestHelper) =>
     try
-      let path = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp.flush")
+      let path = FilePath(h.env.root as AmbientAuth, "tmp.flush")
       with file = CreateFile(path) as File do
         // Flush with no writes succeeds trivially, but does nothing.
         h.assert_true(file.flush())
@@ -910,7 +927,7 @@ class iso _TestFileFlush is UnitTest
 class iso _TestFileReadMore is UnitTest
   fun name(): String => "files/File.read-more"
   fun apply(h: TestHelper)? =>
-    let path = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp-read-more")
+    let path = FilePath(h.env.root as AmbientAuth, "tmp-read-more")
     with file = CreateFile(path) as File do
       h.assert_true(file.write("foobar"))
     end
@@ -933,7 +950,7 @@ class iso _TestFileReadMore is UnitTest
 class iso _TestFileRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-file"
   fun apply(h: TestHelper) ? =>
-    let path = FilePath(FileAuth(h.env.root as AmbientAuth), "tmp-read-only")
+    let path = FilePath(h.env.root as AmbientAuth, "tmp-read-only")
     try
       with file = CreateFile(path) as File do
         None
@@ -955,7 +972,7 @@ class iso _TestDirectoryRemoveReadOnly is UnitTest
   fun name(): String => "files/File.remove-readonly-directory"
 
   fun apply(h: TestHelper) ? =>
-    let path = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "tmp-read-only-dir")?
+    let path = FilePath.mkdtemp(h.env.root as AmbientAuth, "tmp-read-only-dir")?
     let dir = Directory(path)?
     try
       let mode: FileMode ref = FileMode
@@ -977,7 +994,7 @@ class iso _TestFileLinesEmptyFile is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "empty")?
+    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "empty")?
 
   fun ref tear_down(h: TestHelper) =>
     try (tmp_dir as FilePath).remove() end
@@ -1023,7 +1040,7 @@ class iso _TestFileLinesSingleLine is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "single-line")?
+    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "single-line")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -1090,7 +1107,7 @@ class _TestFileLinesMultiLine is UnitTest
   ]
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "multi-line")?
+    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "multi-line")?
 
   fun ref tear_down(h: TestHelper) =>
     try
@@ -1135,7 +1152,7 @@ class _TestFileLinesMovingCursor is UnitTest
   var tmp_dir: (FilePath | None) = None
 
   fun ref set_up(h: TestHelper) ? =>
-    tmp_dir = FilePath.mkdtemp(FileAuth(h.env.root as AmbientAuth), "moving-cursor")?
+    tmp_dir = FilePath.mkdtemp(h.env.root as AmbientAuth, "moving-cursor")?
 
   fun ref tear_down(h: TestHelper) =>
     try
diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index e743770c41..370bc60b5d 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -54,7 +54,7 @@ class val FilePath
     """
 
   new val create(
-    base: FileAuth,
+    base: (AmbientAuth | FileAuth),
     path': String,
     caps': FileCaps val = recover val FileCaps .> all() end)
   =>
@@ -96,7 +96,7 @@ class val FilePath
     path = tmp_path
 
   new val mkdtemp(
-    base: (FilePath | FileAuth),
+    base: (AmbientAuth | FileAuth | FilePath),
     prefix: String = "",
     caps': FileCaps val = recover val FileCaps .> all() end) ?
   =>
@@ -114,6 +114,7 @@ class val FilePath
     """
     (let dir, let pre) = Path.split(prefix)
     let parent: FilePath = match base
+      | let base': AmbientAuth => FilePath(base', dir)
       | let base': FileAuth => FilePath(base', dir)
       | let base': FilePath => FilePath.from(base', dir)?
     end

From 75759bc17c89ceba8e4116209f8f69538b690a66 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Tue, 31 Aug 2021 21:05:48 -0500
Subject: [PATCH 19/26] Docstring clarity

---
 packages/files/file_path.pony | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index 370bc60b5d..72946bad25 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -102,14 +102,13 @@ class val FilePath
   =>
     """
     Create a temporary directory and returns a path to it. The directory's name
-    will begin with `prefix`. The caller must either provide the root
-    capability or an existing FilePath.
+    will begin with `prefix`.
 
-    If FileAuth is provided, pattern will be relative to the program's
+    If `AmbientAuth` or `FileAuth` are provided, pattern will be relative to the program's
     working directory. Otherwise, it will be relative to the existing
-    FilePath, and the existing FilePath must be a prefix of the resulting path.
+    `FilePath`, and the existing `FilePath` must be a prefix of the resulting path.
 
-    The resulting FilePath will have capabilities that are the intersection of
+    The resulting `FilePath` will have capabilities that are the intersection of
     the supplied capabilities and the capabilities on the base.
     """
     (let dir, let pre) = Path.split(prefix)

From 65816511fb70e1fb37c37bcc13570f13af88af7f Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Tue, 31 Aug 2021 21:17:30 -0500
Subject: [PATCH 20/26] Update with AmbientAuth in union

---
 .release-notes/split-filepath.md | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/.release-notes/split-filepath.md b/.release-notes/split-filepath.md
index d57ed6290e..d9eee5a31f 100644
--- a/.release-notes/split-filepath.md
+++ b/.release-notes/split-filepath.md
@@ -1,10 +1,10 @@
 ## Split `FilePath` construction into two methods
 
-`FilePath` previously had only one constructor, the default `create`, which used a union of `(AmbientAuth | FilePath)`. The first half of this union `AmbientAuth` could never `error`, while the second `FilePath` could `error`. By splitting construction into two methods, we now have a default `create` constructor which cannot `error` and a new `from` constructor which can `error`. The default `create` constructor uses a new "files" package root authority `FileAuth` rather than global root authority `AmbientAuth`, while the new `from` constructor uses `FilePath`.
+`FilePath` previously had only one constructor, the default `create`, which used a union of `(AmbientAuth | FilePath)`. The first half of this union `AmbientAuth` could never `error`, while the second `FilePath` could `error`. By splitting construction into two methods, we now have a default `create` constructor which cannot `error` and a new `from` constructor which can `error`. The default `create` constructor now accepts a new "files" package root authority `FileAuth` as well as the global root authority `AmbientAuth`, while the new `from` constructor uses `FilePath`.
 
-The result of this change is that three user changes are needed, namely around `create`, `from`, and `mkdtemp`.
+The result of this change is that three user changes are needed, namely around `create`, `from`, and `mkdtemp`. Any place where previously `AmbientAuth` was accepted now also accepts `FileAuth`.
 
-Before `create` using `AmbientAuth` to now `create` using `FileAuth`:
+Before `create` using `AmbientAuth` to now `create` using `AmbientAuth` or `FileAuth` -- note can no longer fail:
 
 ```pony
 let ambient: AmbientAuth = ...
@@ -15,7 +15,14 @@ becomes
 
 ```pony
 let ambient: AmbientAuth = ...
-let filepath: FilePath = FilePath(FileAuth(ambient), path)
+let filepath: FilePath = FilePath(ambient, path)
+```
+
+or 
+
+```pony
+let fileauth: FileAuth = ...
+let filepath: FilePath = FilePath(fileauth, path)
 ```
 
 ---
@@ -36,7 +43,7 @@ let subpath = FilePath.from(filepath, path)?
 
 ---
 
-Before `mkdtemp` using `AmbientAuth` to now `mkdtemp` using `FileAuth`:
+Before `mkdtemp` using `AmbientAuth` to now `mkdtemp` using `AmbientAuth` or `FileAuth` -- note can still fail:
 
 ```pony
 let ambient: AmbientAuth = ...
@@ -47,5 +54,10 @@ becomes
 
 ```pony
 let ambient: AmbientAuth = ...
-let tempdir = FilePath.mkdtemp(FileAuth(ambient), prefix)?
+let tempdir = FilePath.mkdtemp(ambient, prefix)?
 ```
+
+```pony
+let fileauth: FileAuth = ...
+let tempdir = FilePath.mkdtemp(fileauth, prefix)?
+```
\ No newline at end of file

From a497c188e24c49c9ac7957577b0c8c91ba6508bf Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Tue, 31 Aug 2021 21:38:09 -0500
Subject: [PATCH 21/26] Revert use of FileAuth over AmbientAuth

---
 examples/files/files.pony           | 2 +-
 examples/mandelbrot/mandelbrot.pony | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/examples/files/files.pony b/examples/files/files.pony
index b12b8db468..53124660ad 100644
--- a/examples/files/files.pony
+++ b/examples/files/files.pony
@@ -7,7 +7,7 @@ actor Main
     try
       let auth = env.root as AmbientAuth
       with file = OpenFile(
-        FilePath(FileAuth(auth), env.args(1)?, caps)) as File
+        FilePath(auth, env.args(1)?, caps)) as File
       do
         env.out.print(file.path.path)
         for line in file.lines() do
diff --git a/examples/mandelbrot/mandelbrot.pony b/examples/mandelbrot/mandelbrot.pony
index c8ef7273d0..ed2f39936c 100644
--- a/examples/mandelbrot/mandelbrot.pony
+++ b/examples/mandelbrot/mandelbrot.pony
@@ -114,7 +114,7 @@ class val Config
     width = cmd.option("width").i64().usize()
     outpath =
       try
-        FilePath(FileAuth(env.root as AmbientAuth), cmd.option("output").string())
+        FilePath(env.root as AmbientAuth, cmd.option("output").string())
       else
         None
       end

From d6bdb270a014d02de3aa56262b42aa28373c27ff Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 1 Sep 2021 20:33:52 -0500
Subject: [PATCH 22/26] RM temp variable

---
 examples/files/files.pony | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/examples/files/files.pony b/examples/files/files.pony
index 53124660ad..21ad10555b 100644
--- a/examples/files/files.pony
+++ b/examples/files/files.pony
@@ -5,9 +5,8 @@ actor Main
     let caps = recover val FileCaps.>set(FileRead).>set(FileStat) end
 
     try
-      let auth = env.root as AmbientAuth
       with file = OpenFile(
-        FilePath(auth, env.args(1)?, caps)) as File
+        FilePath(env.root as AmbientAuth, env.args(1)?, caps)) as File
       do
         env.out.print(file.path.path)
         for line in file.lines() do

From 01b10cfac16e521cd909575f4284a101c5f20827 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 1 Sep 2021 20:39:59 -0500
Subject: [PATCH 23/26] Clarify docstring re: capabilities

---
 packages/files/file_path.pony | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index 72946bad25..8ba91e2ccf 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -59,11 +59,11 @@ class val FilePath
     caps': FileCaps val = recover val FileCaps .> all() end)
   =>
     """
-    Create a new path.
+    Create a new path to any location.
 
     Unless absolute, path' will be relative to the program's working directory.
 
-    Capabilities are as provided, unlike with `FilePath.from(...)`.
+    Capabilities are exactly as given.
     """
     caps.union(caps')
     path = Path.abs(path')

From ae327e820bbbc501028c09d28e7ee95fee1675fc Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 1 Sep 2021 20:48:20 -0500
Subject: [PATCH 24/26] RM talk of pattern and reformat to style guide

---
 packages/files/file_path.pony | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/packages/files/file_path.pony b/packages/files/file_path.pony
index 8ba91e2ccf..02076fda1c 100644
--- a/packages/files/file_path.pony
+++ b/packages/files/file_path.pony
@@ -104,12 +104,13 @@ class val FilePath
     Create a temporary directory and returns a path to it. The directory's name
     will begin with `prefix`.
 
-    If `AmbientAuth` or `FileAuth` are provided, pattern will be relative to the program's
-    working directory. Otherwise, it will be relative to the existing
-    `FilePath`, and the existing `FilePath` must be a prefix of the resulting path.
+    If `AmbientAuth` or `FileAuth` are provided, the resulting `FilePath` will
+    be relative to the program's working directory. Otherwise, it will be
+    relative to the existing `FilePath`, and the existing `FilePath` must be a
+    prefix of the resulting path.
 
-    The resulting `FilePath` will have capabilities that are the intersection of
-    the supplied capabilities and the capabilities on the base.
+    The resulting `FilePath` will have capabilities that are the intersection
+    of the supplied capabilities and the capabilities on the base.
     """
     (let dir, let pre) = Path.split(prefix)
     let parent: FilePath = match base

From 135578ddca6fd615fc4a349eea24ab4a2618d6b1 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 1 Sep 2021 20:52:10 -0500
Subject: [PATCH 25/26] FileAuth(auth) -> auth

---
 packages/process/_test.pony | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/packages/process/_test.pony b/packages/process/_test.pony
index cd98bc84bb..10c36911ce 100644
--- a/packages/process/_test.pony
+++ b/packages/process/_test.pony
@@ -40,7 +40,7 @@ class _PathResolver
             break
               recover val
                 Iter[String]((consume paths).values())
-                  .map[FilePath]({(str_path) => FilePath(FileAuth(auth), str_path)})
+                  .map[FilePath]({(str_path) => FilePath(auth, str_path)})
                   .collect[Array[FilePath] ref](Array[FilePath](size))
               end
           end
@@ -133,7 +133,7 @@ class iso _TestFileExecCapabilityIsRequired is UnitTest
       let path_resolver = _PathResolver(h.env.vars, auth)
       let path =
         FilePath(
-          FileAuth(auth),
+          auth,
           _CatCommand.path(path_resolver)?,
           recover val FileCaps .> all() .> unset(FileExec) end)
       let args: Array[String] val = ["dontcare"]
@@ -160,7 +160,7 @@ class iso _TestNonExecutablePathResultsInExecveError is UnitTest
   fun apply(h: TestHelper) =>
     try
       let auth = h.env.root as AmbientAuth
-      let path = FilePath.mkdtemp(FileAuth(auth), "pony_execve_test")?
+      let path = FilePath.mkdtemp(auth, "pony_execve_test")?
       let args: Array[String] val = []
       let vars: Array[String] val = []
 
@@ -213,7 +213,7 @@ class iso _TestStdinStdout is UnitTest
     try
       let auth = h.env.root as AmbientAuth
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
+      let path = FilePath(auth, _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
@@ -252,7 +252,7 @@ class iso _TestStderr is UnitTest
       let auth = h.env.root as AmbientAuth
       let path_resolver = _PathResolver(h.env.vars, auth)
       let path = FilePath(
-        FileAuth(auth),
+        auth,
         ifdef windows then
           "C:\\Windows\\System32\\cmd.exe"
         else
@@ -325,7 +325,7 @@ class iso _TestExpect is UnitTest
     try
       let auth = h.env.root as AmbientAuth
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _EchoPath(path_resolver)?)
+      let path = FilePath(auth, _EchoPath(path_resolver)?)
       let args: Array[String] val = ifdef windows then
         ["cmd"; "/c"; "echo"; "hello carl"]
       else
@@ -358,7 +358,7 @@ class iso _TestWritevOrdering is UnitTest
     try
       let auth = h.env.root as AmbientAuth
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
+      let path = FilePath(auth, _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
@@ -390,7 +390,7 @@ class iso _TestPrintvOrdering is UnitTest
     try
       let auth = h.env.root as AmbientAuth
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
+      let path = FilePath(auth, _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
@@ -432,7 +432,7 @@ class iso _TestStdinWriteBuf is UnitTest
     try
       let auth = h.env.root as AmbientAuth
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _CatCommand.path(path_resolver)?)
+      let path = FilePath(auth, _CatCommand.path(path_resolver)?)
       let args: Array[String] val = _CatCommand.args()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
@@ -477,13 +477,13 @@ class _TestChdir is UnitTest
       + (ifdef windows then 2 else 1 end), "", 0, h)
     try
       let auth = h.env.root as AmbientAuth
-      let path = FilePath(FileAuth(auth), _PwdPath())
+      let path = FilePath(auth, _PwdPath())
       let args: Array[String] val = _PwdArgs()
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
 
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path,
-          args, vars, FilePath(FileAuth(auth), parent))
+          args, vars, FilePath(auth, parent))
       pm.done_writing()
       h.dispose_when_done(pm)
       h.long_test(30_000_000_000)
@@ -504,13 +504,13 @@ class _TestBadChdir is UnitTest
       _ProcessClient(0, "", _EXOSERR(), h, ProcessError(ChdirError))
     try
       let auth = h.env.root as AmbientAuth
-      let path = FilePath(FileAuth(auth), _PwdPath())
+      let path = FilePath(auth, _PwdPath())
       let args: Array[String] val = _PwdArgs()
       let vars: Array[String] iso = recover Array[String](0) end
 
       let pm: ProcessMonitor =
         ProcessMonitor(auth, auth, consume notifier, path,
-          args, consume vars, FilePath(FileAuth(auth), badpath))
+          args, consume vars, FilePath(auth, badpath))
       pm.done_writing()
       h.dispose_when_done(pm)
       h.long_test(30_000_000_000)
@@ -539,9 +539,9 @@ class _TestBadExec is UnitTest
   fun ref set_up(h: TestHelper) ? =>
     let auth = h.env.root as AmbientAuth
     ifdef windows then
-      _bad_exec_path = FilePath(FileAuth(auth), "C:\\Windows\\system.ini")
+      _bad_exec_path = FilePath(auth, "C:\\Windows\\system.ini")
     else
-      let tmp_dir = FilePath.mkdtemp(FileAuth(auth), "pony_stdlib_test_process_bad_exec")?
+      let tmp_dir = FilePath.mkdtemp(auth, "pony_stdlib_test_process_bad_exec")?
       _tmp_dir = tmp_dir
       let bad_exec_path = tmp_dir.join("_bad_exec.sh")?
       _bad_exec_path = bad_exec_path
@@ -601,7 +601,7 @@ class iso _TestLongRunningChild is UnitTest
 
     try
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _SleepCommand.path(path_resolver)?)
+      let path = FilePath(auth, _SleepCommand.path(path_resolver)?)
       h.log(path.path)
       let args = _SleepCommand.args(where seconds = 2)
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]
@@ -659,7 +659,7 @@ class iso _TestKillLongRunningChild is UnitTest
 
     try
       let path_resolver = _PathResolver(h.env.vars, auth)
-      let path = FilePath(FileAuth(auth), _SleepCommand.path(path_resolver)?)
+      let path = FilePath(auth, _SleepCommand.path(path_resolver)?)
       h.log(path.path)
       let args = _SleepCommand.args(where seconds = 2)
       let vars: Array[String] val = ["HOME=/"; "PATH=/bin"]

From 6eb0a20dfc90713adced695d9cff6125ca2d2d64 Mon Sep 17 00:00:00 2001
From: Ryan Hagenson <Ryan.Hagenson@gmail.com>
Date: Wed, 1 Sep 2021 21:03:22 -0500
Subject: [PATCH 26/26] Clarify before and after descriptions of changes

---
 .release-notes/split-filepath.md | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/.release-notes/split-filepath.md b/.release-notes/split-filepath.md
index d9eee5a31f..b7549fe0bd 100644
--- a/.release-notes/split-filepath.md
+++ b/.release-notes/split-filepath.md
@@ -4,14 +4,14 @@
 
 The result of this change is that three user changes are needed, namely around `create`, `from`, and `mkdtemp`. Any place where previously `AmbientAuth` was accepted now also accepts `FileAuth`.
 
-Before `create` using `AmbientAuth` to now `create` using `AmbientAuth` or `FileAuth` -- note can no longer fail:
+Prior to this change, `create` could be used with `AmbientAuth` as in:
 
 ```pony
 let ambient: AmbientAuth = ...
 let filepath: FilePath = FilePath(ambient, path)?
 ```
 
-becomes
+After this change, `create` can be used with `AmbientAuth` or `FileAuth` -- note that this can no longer fail:
 
 ```pony
 let ambient: AmbientAuth = ...
@@ -27,14 +27,14 @@ let filepath: FilePath = FilePath(fileauth, path)
 
 ---
 
-Before `create` using `FilePath` to now `from` using `FilePath`:
+Prior to this change, `create` could be used with `FilePath` as in:
 
 ```pony
 let filepath: FilePath = ...
 let subpath = FilePath(filepath, path)?
 ```
 
-becomes
+After this change, construction with an existing `FilePath` must use `from`:
 
 ```pony
 let filepath: FilePath = ...
@@ -43,20 +43,22 @@ let subpath = FilePath.from(filepath, path)?
 
 ---
 
-Before `mkdtemp` using `AmbientAuth` to now `mkdtemp` using `AmbientAuth` or `FileAuth` -- note can still fail:
+Prior to this change, `mkdtemp` could be used with `AmbientAuth` or `FilePath` as in:
 
 ```pony
 let ambient: AmbientAuth = ...
 let tempdir = FilePath.mkdtemp(ambient, prefix)?
 ```
 
-becomes
+or
 
 ```pony
-let ambient: AmbientAuth = ...
-let tempdir = FilePath.mkdtemp(ambient, prefix)?
+let filepath: FilePath = ...
+let tempdir = FilePath.mkdtemp(filepath, prefix)?
 ```
 
+After this change, `mkdtemp` can also use `FileAuth` -- note can still fail:
+
 ```pony
 let fileauth: FileAuth = ...
 let tempdir = FilePath.mkdtemp(fileauth, prefix)?