Add ListAppend

Signed-off-by: Alex Humphreys <alex.humphreys@here.com>

Idrall/Check.idr

@@ -64,6 +64,9 @@ mutual
   aEquivHelper i ns1 (EListLit tx xs) ns2 (EListLit ty ys)
     = aEquivMaybe i ns1 tx ns2 ty &&
       aEquivList i ns1 xs ns2 ys
+  aEquivHelper i ns1 (EListAppend w x) ns2 (EListAppend y z)
+    = aEquivHelper i ns1 w ns2 y &&
+      aEquivHelper i ns1 x ns2 z
   aEquivHelper _ _ _ _ _ = False
   -- TODO check if assert/equivalent should be in here
 
@@ -144,8 +147,9 @@ mutual
     | NEquivalent Neutral Normal
     | NAssert Neutral
     | NApp Neutral Normal
-    | NList Neutral
     | NBoolAnd Neutral Normal
+    | NList Neutral
+    | NListAppend Neutral Normal
 
   Show Value where
     show (VLambda x y) = "(VLambda " ++ show x ++ " " ++ show y ++ ")"
@@ -168,6 +172,7 @@ mutual
     show (NAssert x) = "(NEquivalent " ++ show x ++ ")"
     show (NApp x y) = "(NApp " ++ show x ++ " " ++ show y ++ ")"
     show (NList x) = "(NList " ++ show x ++ ")"
+    show (NListAppend x y) = "(NListAppend " ++ show x ++ " " ++ show y ++ ")"
     show (NBoolAnd x y) = "(NBoolAnd " ++ show x ++ " " ++ show y ++ ")"
 
 extendEnv : Env -> Name -> Value -> Env
@@ -215,6 +220,7 @@ data Error
   | ReadBackError String
   | SortError
   | AssertError String
+  | ListAppendError String
 
 public export
 Show Error where
@@ -227,6 +233,7 @@ Show Error where
   show (ReadBackError x) = "ReadBackError: " ++ x
   show SortError = "SortError"
   show (AssertError str) = "AssertError" ++ str
+  show (ListAppendError str) = "ListAppendError" ++ str
 
 mutual
   partial
@@ -294,6 +301,10 @@ mutual
     ty' <- eval env ty
     vs <- mapListEither es (eval env)
     Right (VListLit (Just ty') vs)
+  eval env (EListAppend x y) = do
+    x' <- eval env x
+    y' <- eval env y
+    doListAppend x' y'
   eval env (ENaturalIsZero x)
     = do x' <- eval env x
          doNaturalIsZero x'
@@ -329,6 +340,13 @@ mutual
     = Right (VNeutral (VEquivalent x y) (NAssert v))
   doAssert x = Left (AssertError ("Assert error: " ++ show x))
 
+  doListAppend : Value -> Value -> Either Error Value
+  doListAppend (VListLit x xs) (VListLit _ ys) =
+    Right (VListLit x (xs ++ ys)) -- TODO dropping type info
+  doListAppend (VNeutral (VList x) v) y =
+    Right (VNeutral (VList x) (NListAppend v (Normal' (VList x) y)))
+  doListAppend x y = Left (ListAppendError (show x ++ " " ++ show y))
+
   -- fresh names
   nextName : Name -> Name
   nextName x = x ++ "'"
@@ -341,6 +359,7 @@ mutual
                                True => freshen used (nextName n)
 
   -- reading back
+  partial
   readBackNeutral : Ctx -> Neutral -> Either Error Expr
   readBackNeutral ctx (NVar x) = Right (EVar x)
   readBackNeutral ctx (NNaturalIsZero x) = do
@@ -364,6 +383,10 @@ mutual
   readBackNeutral ctx (NList a) = do
     a' <- readBackNeutral ctx a
     Right (EList a')
+  readBackNeutral ctx (NListAppend x y) = do
+    x' <- readBackNeutral ctx x
+    y' <- readBackNormal ctx y
+    Right (EListAppend x' y')
 
   readBackTyped : Ctx -> Ty -> Value -> Either Error Expr
   readBackTyped ctx (VPi dom ran) fun =
@@ -431,7 +454,7 @@ isBool ctx other = unexpected ctx "Not Bool" other
 
 isList : Ctx -> Value -> Either Error ()
 isList ctx (VList x) = Right ()
-isList ctx other = unexpected ctx "Not Bool" other
+isList ctx other = unexpected ctx "Not List" other
 
 isEquivalent : Ctx -> Value -> Either Error (Value, Value)
 isEquivalent ctx (VEquivalent x y) = Right (x, y)
@@ -603,3 +626,9 @@ mutual
     mapListEither xs (\e => check ctx e xTy)
     Right (xTy)
   synth ctx (EAssert other) = Left (AssertError ("Can't assert for expr: " ++ show other))
+  synth ctx (EListAppend x y) = do
+    xTy <- synth ctx x
+    yTy <- synth ctx y
+    isList ctx xTy
+    convert ctx (VConst CType) xTy yTy
+    Right (xTy)

Idrall/Expr.idr

@@ -59,6 +59,8 @@ data Expr
   | EList Expr
   -- | > EList (Some e) [e', ...] ~ [] : List a
   | EListLit (Maybe Expr) (List Expr)
+  -- | > x # y
+  | EListAppend Expr Expr
 
 export
 Show Expr where
@@ -81,3 +83,4 @@ Show Expr where
   show (EList x) = "(EList " ++ show x ++ ")"
   show (EListLit Nothing xs) = "(EListLit Nothing " ++ show xs ++ ")"
   show (EListLit (Just x) xs) = "(EListLit (Just " ++ show x ++ ") " ++ show xs ++ ")"
+  show (EListAppend x y) = "(EListAppend " ++ show x ++ " " ++ show y ++ ")"

Idrall/Parser.idr

@@ -95,7 +95,8 @@ table = [ [ Infix appl AssocLeft]
         , [ Infix (do token ":"; pure EAnnot) AssocLeft]
         , [ Infix (do (token "===" <|> token "≡"); pure EEquivalent) AssocLeft]
         , [ Prefix (do token "assert"; token ":"; pure EAssert)]
-        , [ Infix (do token "&&"; pure EBoolAnd) AssocLeft]]
+        , [ Infix (do token "&&"; pure EBoolAnd) AssocLeft]
+        , [ Infix (do token "#"; pure EListAppend) AssocLeft]]
 
 mutual
   letExpr : Parser Expr -- TODO handle type annotation

tests/Test.idr

@@ -79,7 +79,7 @@ testAll = do
       putStrLn "done"
 
 expectPass : List String
-expectPass = ["AssertTrivial", "Bool", "Function", "Natural", "True", "NaturalIsZero", "NaturalLiteral", "Let", "FunctionTypeTermTerm", "FunctionApplication", "Equivalence", "FunctionDependentType1", "List", "ListLiteralOne", "ListLiteralEmpty"]
+expectPass = ["AssertTrivial", "Bool", "Function", "Natural", "True", "NaturalIsZero", "NaturalLiteral", "Let", "FunctionTypeTermTerm", "FunctionApplication", "Equivalence", "FunctionDependentType1", "List", "ListLiteralOne", "ListLiteralEmpty", "OperatorListConcatenate"]
 
 testGood : IO ()
 testGood