[NO-ISSUE] Add traverse_ to Prelude!

.github/workflows/build.yaml

@@ -19,15 +19,14 @@ jobs:
     strategy:
       matrix:
         ghc:
-          - 8.10.7
-          - 9.2.3
+          - 9.2.4
     steps:
       - uses: actions/checkout@v3
       - uses: haskell/actions/setup@v2
         id: setup-haskell
         with:
           ghc-version: ${{ matrix.ghc }}
-          cabal-version: 3.6.2.0
+          cabal-version: 3.8.1.0
       - name: Create freeze file
         run: cabal freeze
       - uses: actions/cache@v3

.github/workflows/formatting.yaml

@@ -0,0 +1,21 @@
+name: Formatting
+
+on:
+  pull_request:
+    paths:
+      - "src/**.hs"
+      - scrive-prelude.cabal
+      - .github/workflows/build.yaml
+  push:
+    branches:
+      - main
+
+jobs:
+  fourmolu:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: fourmolu/fourmolu-action@v5
+        with:
+          pattern: |
+            src/**/*.hs

fourmolu.yaml

@@ -0,0 +1,11 @@
+indentation: 2
+function-arrows: leading # where to place arrows in type signatures
+comma-style: leading # for lists, tuples etc. - can also be 'trailing'
+import-export-style: leading
+indent-wheres: true # 'false' means save space by only half-indenting the 'where' keyword
+record-brace-space: true # rec {x = 1} vs. rec{x = 1}
+newlines-between-decls: 1 # number of newlines between top-level declarations
+haddock-style: single-line # '--' vs. '{-'
+let-style: inline
+in-style: left-align
+respectful: true # don't be too opinionated about newlines etc

src/Prelude.hs

@@ -1,8 +1,9 @@
--- | Slightly customized replacement of Prelude.
-{-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# LANGUAGE PackageImports #-}
-module Prelude (
-    module Control.Applicative
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+-- | Slightly customized replacement of Prelude.
+module Prelude
+  ( module Control.Applicative
   , module Control.Monad
   , module Data.Algebra.Boolean
   , module Data.Either
@@ -18,88 +19,161 @@ module Prelude (
   , MonadFail (..)
   , (!!)
   -- optics
-  , (&), (%), (?~)
-  , view, (^.)
-  , preview, (^?)
-  , toListOf, (^..)
-  , over, (%~)
-  , set, (.~)
+  , (&)
+  , (%)
+  , (?~)
+  , view
+  , (^.)
+  , preview
+  , (^?)
+  , toListOf
+  , (^..)
+  , over
+  , (%~)
+  , set
+  , (.~)
   , copy
   -- prelude
-  , identity
+  , expectJust
   , for
-  , maybeRead
-  , toMaybe
+  , fromJust
   , head
+  , identity
   , last
   , maximum
+  , maybeRead
   , minimum
   , read
+  , showt
+  , showtp
   , tail
-  , expectJust
-  , fromJust
+  , throwLeft
+  , toMaybe
+  , unexpectedError
   , whenJust
   , whenNothing
-  , unexpectedError
-  , throwLeft
-  , showt
-  , showtp
-  ) where
+  )
+where
 
 import Control.Applicative
 import Control.Exception (Exception)
 import Control.Monad hiding (fail)
-import Control.Monad.Catch (MonadThrow(..))
+import Control.Monad.Catch (MonadThrow (..))
 import Control.Monad.Extra hiding (fail)
-import Control.Monad.Fail (MonadFail(..))
+import Control.Monad.Fail (MonadFail (..))
 import Data.Algebra.Boolean
 import Data.Either
-import Data.Foldable (asum, foldMap)
+import qualified Data.Either.Optics as O
+import Data.Foldable (asum, foldMap, traverse_)
 import Data.List hiding
-  ( (!!), all, and, any, head, last, maximum, minimum, or, tail
+  ( all
+  , and
+  , any
+  , head
+  , last
+  , maximum
+  , minimum
+  , or
+  , tail
+  , (!!)
   )
 import Data.Maybe hiding (fromJust)
+import qualified Data.Maybe.Optics as O
 import Data.Monoid
 import Data.Monoid.Utils
 import Data.Text (Text)
+import qualified Data.Text as T
+import qualified Data.Text.Lazy as TL
+import qualified Data.Tuple.Optics as O
 import GHC.Generics (Generic)
 import GHC.Stack (HasCallStack, withFrozenCallStack)
 import Optics
+import qualified Optics as O
+  ( A_Fold
+  , A_Getter
+  , A_Lens
+  , A_Prism
+  , A_ReversedLens
+  , A_ReversedPrism
+  , A_Review
+  , A_Setter
+  , A_Traversal
+  , AffineFold
+  , AffineTraversal
+  , AffineTraversal'
+  , An_AffineFold
+  , An_AffineTraversal
+  , An_Iso
+  , Fold
+  , Getter
+  , Iso
+  , Iso'
+  , IxAffineFold
+  , IxAffineTraversal
+  , IxAffineTraversal'
+  , IxFold
+  , IxGetter
+  , IxLens
+  , IxLens'
+  , IxSetter
+  , IxSetter'
+  , IxTraversal
+  , IxTraversal'
+  , Lens
+  , Lens'
+  , NoIx
+  , Optic
+  , Optic'
+  , Prism
+  , Prism'
+  , ReversedLens
+  , ReversedLens'
+  , ReversedPrism
+  , ReversedPrism'
+  , Review
+  , Setter
+  , Setter'
+  , Traversal
+  , Traversal'
+  , WithIx
+  )
 import Text.JSON.FromJSValue
 import Text.JSON.ToJSValue
 import Text.Pretty.Simple
-  ( OutputOptions(..), defaultOutputOptionsDarkBg, pShowOpt
+  ( OutputOptions (..)
+  , defaultOutputOptionsDarkBg
+  , pShowOpt
   )
 import "base" Prelude hiding
-  ( (!!), (&&), (||), all, and, any, error, fail, head, id, last, maximum
-  , minimum, not, or, read, tail
-  )
-import qualified Data.Either.Optics as O
-import qualified Data.Maybe.Optics as O
-import qualified Data.Text as T
-import qualified Data.Text.Lazy as TL
-import qualified Data.Tuple.Optics as O
-import qualified Optics as O
-  ( A_Fold, A_Getter, A_Lens, A_Prism, A_ReversedLens, A_ReversedPrism, A_Review
-  , A_Setter, A_Traversal, AffineFold, AffineTraversal, AffineTraversal'
-  , An_AffineFold, An_AffineTraversal, An_Iso, Fold, Getter, Iso, Iso'
-  , IxAffineFold, IxAffineTraversal, IxAffineTraversal', IxFold, IxGetter
-  , IxLens, IxLens', IxSetter, IxSetter', IxTraversal, IxTraversal', Lens, Lens'
-  , NoIx, Optic, Optic', Prism, Prism', ReversedLens, ReversedLens'
-  , ReversedPrism, ReversedPrism', Review, Setter, Setter', Traversal
-  , Traversal', WithIx
+  ( all
+  , and
+  , any
+  , error
+  , fail
+  , head
+  , id
+  , last
+  , maximum
+  , minimum
+  , not
+  , or
+  , read
+  , tail
+  , (!!)
+  , (&&)
+  , (||)
   )
 import qualified "base" Prelude as P hiding (fail)
 
 -- | Boolean algebra of functions.
 instance Boolean b => Boolean (a -> b) where
-  true  = const true
+  true = const true
   false = const false
   not f = not . f
-  (&&)   = liftA2 (&&)
-  (||)   = liftA2 (||)
-  xor    = liftA2 xor
-  (-->)  = liftA2 (-->)
+  (&&) = liftA2 (&&)
+  (||) = liftA2 (||)
+  xor = liftA2 xor
+  (-->) = liftA2 (-->)
   (<-->) = liftA2 (<-->)
 
 instance FromJSValue Text where
@@ -112,6 +186,7 @@ instance ToJSValue Text where
 -- Additional optics utilities.
 
 {-# ANN copy ("HLint: ignore Eta reduce" :: String) #-}
+
 -- | Copy the field value from an object of the same type.
 copy :: (Is k A_Setter, Is k A_Getter) => Optic k is s s a a -> s -> s -> s
 copy x fromThis toThat = set x (view x fromThis) toThat
@@ -126,11 +201,11 @@ for = flip map
 maybeRead :: Read a => Text -> Maybe a
 maybeRead s = case reads (T.unpack s) of
   [(v, "")] -> Just v
-  _         -> Nothing
+  _ -> Nothing
 
 -- | Returns Just if the precondition is true.
 toMaybe :: Bool -> a -> Maybe a
-toMaybe True  x = Just x
+toMaybe True x = Just x
 toMaybe False _ = Nothing
 
 ----------------------------------------
@@ -143,14 +218,15 @@ identity = P.id
 (!!) :: HasCallStack => [a] -> Int -> a
 xs !! n
   | n < 0 = negativeIndexError "!!"
-  | otherwise = foldr
-    (\x r k -> case k of
-      0 -> x
-      _ -> r (k - 1)
-    )
-    (indexOutOfBoundsError "!!")
-    xs
-    n
+  | otherwise =
+      foldr
+        ( \x r k -> case k of
+            0 -> x
+            _ -> r (k - 1)
+        )
+        (indexOutOfBoundsError "!!")
+        xs
+        n
 
 -- | Replacement for 'P.head' that provides useful information on failure.
 head :: HasCallStack => [a] -> a
@@ -177,22 +253,22 @@ read :: (HasCallStack, Read a, Show a) => Text -> a
 read s =
   let parsedS = reads $ T.unpack s
   in  fromMaybe
-          (  unexpectedError
-          $  "reading failed (input was '"
-          <> s
-          <> "', reads returned '"
-          <> showt parsedS
-          <> "')"
-          )
+        ( unexpectedError $
+            "reading failed (input was '"
+              <> s
+              <> "', reads returned '"
+              <> showt parsedS
+              <> "')"
+        )
         $ do
-            [(v, "")] <- return parsedS
-            return v
+          [(v, "")] <- return parsedS
+          return v
 
 -- | General version of 'fromJust' with a custom error message
 expectJust :: HasCallStack => Text -> Maybe a -> a
 expectJust msg = \case
   Nothing -> unexpectedError msg
-  Just a  -> a
+  Just a -> a
 
 -- | Replacement for 'Data.Maybe.fromJust' that provides useful
 -- information on failure.
@@ -202,7 +278,7 @@ fromJust = expectJust "fromJust received Nothing"
 -- | whenNothing mA fa = maybe fa return mA
 whenNothing :: Applicative f => Maybe a -> f a -> f a
 whenNothing (Just x) _ = pure x
-whenNothing Nothing  m = m
+whenNothing Nothing m = m
 
 -- | Like 'error', but with a more conspicous name.
 unexpectedError :: HasCallStack => Text -> a
@@ -231,8 +307,11 @@ showt = T.pack . show
 
 -- | Pretty print anything with a `Show` instance.
 showtp :: Show a => a -> T.Text
-showtp = TL.toStrict . pShowOpt
-  (defaultOutputOptionsDarkBg { outputOptionsCompact   = True
-                              , outputOptionsPageWidth = 180
-                              }
-  )
+showtp =
+  TL.toStrict
+    . pShowOpt
+      ( defaultOutputOptionsDarkBg
+          { outputOptionsCompact = True
+          , outputOptionsPageWidth = 180
+          }
+      )