From 10feb2dc8ad775a64b6db4d19c76bd6fa38044a8 Mon Sep 17 00:00:00 2001
From: Arnaud Bailly <arnaud@pankzsoft.com>
Date: Wed, 5 Nov 2025 12:07:48 +0100
Subject: fix resolution of free variables

---
 lambda-calcul/haskell/src/Minilang/Lambda.hs          | 4 ++--
 lambda-calcul/haskell/src/Minilang/Lambda/DeBruijn.hs | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

(limited to 'lambda-calcul/haskell/src')

diff --git a/lambda-calcul/haskell/src/Minilang/Lambda.hs b/lambda-calcul/haskell/src/Minilang/Lambda.hs
index 2372578..d223658 100644
--- a/lambda-calcul/haskell/src/Minilang/Lambda.hs
+++ b/lambda-calcul/haskell/src/Minilang/Lambda.hs
@@ -22,8 +22,8 @@ loadProgram language env context exprs =
   fmap (\(res, e, c) -> (reverse res, e, c)) result
   where
     result =
-      foldr
-        ( \expr acc ->
+      foldl
+        ( \acc expr ->
             case acc of
               Left typeError -> Left typeError
               Right (results, env', context') ->
diff --git a/lambda-calcul/haskell/src/Minilang/Lambda/DeBruijn.hs b/lambda-calcul/haskell/src/Minilang/Lambda/DeBruijn.hs
index de179ad..025fd39 100644
--- a/lambda-calcul/haskell/src/Minilang/Lambda/DeBruijn.hs
+++ b/lambda-calcul/haskell/src/Minilang/Lambda/DeBruijn.hs
@@ -47,14 +47,16 @@ eval (App f a) =
     f' -> App f' a
 eval term = term
 
-eval' :: Show ann => Env ann -> DeBruijn ann -> DeBruijn ann
+eval' :: (Show ann, Eq ann) => Env ann -> DeBruijn ann -> DeBruijn ann
 eval' env (FV v) = case lookup v env of
   Just term -> term
   Nothing -> FV v
 eval' env (App f a) =
   case eval' env f of
     Lam _ body -> eval' env (substitute env 0 a body)
-    f' -> eval' env $ App f' a
+    f' -> if f' /= f
+          then eval' env $ App f' a
+          else App f' a
 eval' _ term = term
 
 substitute :: Env ann -> Int -> DeBruijn ann -> DeBruijn ann -> DeBruijn ann
-- 
cgit v1.3.1