feat: can desugar expressions

1 files changed, 16 insertions, 0 deletions

diff --git a/lambda-calcul/haskell/src/Minilang/Lambda/Parser.hs b/lambda-calcul/haskell/src/Minilang/Lambda/Parser.hs
index 28da47f..37834d3 100644
--- a/lambda-calcul/haskell/src/Minilang/Lambda/Parser.hs
+++ b/lambda-calcul/haskell/src/Minilang/Lambda/Parser.hs
@@ -11,6 +11,8 @@ import Data.Void (Void)
 import Text.Megaparsec (Parsec, between, empty, errorBundlePretty, manyTill, notFollowedBy, optional, parse, try)
 import Text.Megaparsec.Char (alphaNumChar, char, letterChar, space1, string, symbolChar)
 import qualified Text.Megaparsec.Char.Lexer as L
+import Minilang.Lambda.Eval (Term)
+import qualified Minilang.Lambda.Eval as Eval
 
 type Parser = Parsec Void Text
 
@@ -20,6 +22,20 @@ data ParseError = ParseError Text
 data AST = Sym Text | Abs [Text] AST | App AST AST [AST]
   deriving (Eq, Show)
 
+desugar :: AST -> Term
+desugar = \case
+  Sym sym -> Eval.Var sym
+  Abs bound body ->
+    foldr
+      Eval.Lam
+      (desugar body)
+      bound
+  App x y rest ->
+    foldl
+      (\acc a -> Eval.App acc (desugar a))
+      (Eval.App (desugar x) (desugar y))
+      rest
+
 pretty :: AST -> Text
 pretty = \case
   Sym sym -> sym