Extracted function

1 files changed, 14 insertions, 8 deletions

diff --git a/src/Compiler.hs b/src/Compiler.hs
index ea97bb8..978e32b 100644
--- a/src/Compiler.hs
+++ b/src/Compiler.hs
@@ -15,6 +15,19 @@ type CompResult = Either [Error] ()
 startState :: CompState
 startState = (emptyEnv, [])
 
+-- | @foldlEither fn init xs@ folds left @xs@ applying a function @fn@ that
+-- returns either, returning accumulated right and the collected lefts as a
+-- list.
+foldlEither :: (accr -> b -> Either accl accr) -> (accr, [accl]) -> [b] -> (accr, [accl])
+foldlEither fn init xs =
+  foldl
+    ( \(r, l) x -> case fn r x of
+        Left e -> (r, e : l)
+        Right x -> (x, l)
+    )
+    init
+    xs
+
 compile :: [A.Expr] -> State CompState CompResult
 compile (x : xs) = do
   case x of
@@ -27,14 +40,7 @@ compile (x : xs) = do
       (nev, nerrs) <-
         return $ case addSymUniq ev (ident, A.toFuncType params ret, pos) of
           Left e -> (ev, e : errs)
-          Right fev ->
-            foldl
-              ( \(ev, errs) (id, typ, pos) -> case addSymUniq ev (id, typ, pos) of
-                  Right ev -> (ev, errs)
-                  Left nerr -> (ev, nerr : errs)
-              )
-              (addEnv fev, errs)
-              params
+          Right fev -> foldlEither addSymUniq (addEnv fev, errs) params
       put (nev, nerrs)
       r <- compile body
       (_, errs) <- get