adt support in type inference

src/Rlp/AltSyntax.hs

@@ -2,7 +2,7 @@
 module Rlp.AltSyntax
     (
     -- * AST
-      Program(..), Decl(..), ExprF(..), Pat(..)
+      Program(..), Decl(..), ExprF(..), Pat(..), pattern ConP'
     , RlpExprF, RlpExpr, Binding(..), Alter(..)
     , RlpExpr', RlpExprF', AnnotatedRlpExpr', Type'
     , DataCon(..), Type(..), Kind
@@ -18,7 +18,7 @@ module Rlp.AltSyntax
     -- * Optics
     , programDecls
     , _VarP, _FunB, _VarB
-    , _TySigD, _FunD
+    , _TySigD, _FunD, _DataD
     , _LetEF
     , Core.applicants1, Core.arrowStops
 
@@ -141,6 +141,20 @@ data Pat b = VarP b
            | AppP (Pat b) (Pat b)
            deriving (Eq, Show, Generic, Generic1)
 
+conList :: Prism' (Pat b) (b, [Pat b])
+conList = prism' up down where
+    up (b,as)               = foldl AppP (ConP b) as
+    down (ConP b)           = Just (b, [])
+    down (AppP (ConP b) as) = Just (b, go as)
+    down _                  = Nothing
+
+    go (AppP f x) = f : go x
+    go p          = [p]
+
+pattern ConP' :: b -> [Pat b] -> Pat b
+pattern ConP' c as <- (preview conList -> Just (c,as))
+    where ConP' c as = review conList (c,as)
+
 deriveShow1 ''Alter
 deriveShow1 ''Binding
 deriveShow1 ''ExprF