fix resolution of free variables

4 files changed, 35 insertions, 9 deletions

diff --git a/lambda-calcul/haskell/bool-prog.lisp b/lambda-calcul/haskell/bool-prog.lisp
new file mode 100644
index 0000000..86fab0a
--- /dev/null
+++ b/lambda-calcul/haskell/bool-prog.lisp
@@ -0,0 +1,19 @@
+(def False (lam (f t) f))
+(def True (lam (f t) t))
+(def Not (lam (b) (b True False)))
+
+(Not True)
+
+(def And (lam (a b) (a False b)))
+(def Or (lam (a b) (a b True)))
+(def If (lam (b x y) (b x y)))
+(def Zero (lam (z s) z))
+(def Succ (lam (n z s) (s n)))
+(def One (Succ Zero))
+(def Two (Succ One))
+(def Three (Succ Two))
+(def IsZero (lam (n) (n True (lam (m) False))))
+
+(Or (IsZero One) (IsZero Two))
+
+(IsZero Zero)
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
diff --git a/lambda-calcul/haskell/test/Minilang/REPLSpec.hs b/lambda-calcul/haskell/test/Minilang/REPLSpec.hs
index aa73b69..851706c 100644
--- a/lambda-calcul/haskell/test/Minilang/REPLSpec.hs
+++ b/lambda-calcul/haskell/test/Minilang/REPLSpec.hs
@@ -90,15 +90,20 @@ spec = parallel $
                      "REPLError \"cannot load file foo in Pure interpreter\""
                    ]
 
-    -- it "can load 'bool-prog.lisp'" $ do
-    --   boolProg <- readFile "bool-prog.lisp"
-    --   let PurerEnv{outputs} = runProgram (loadProgramInEnv boolProg)
-    --   outputs `shouldBe` []
+    it "can load 'bool-prog.lisp'" $ do
+      boolProg <- readFile "bool-prog.lisp"
+      let PurerEnv{outputs} = runProgram (loadProgramInEnv boolProg)
+      outputs `shouldBe` []
 
     it "can load 'bool.lisp'" $ do
       boolProg <- readFile "bool.lisp"
       let PurerEnv {outputs} = runProgram (loadProgramInEnv boolProg)
-      outputs `shouldBe` [Evaluated (Abs ["f", "t"] (Sym "f")) (Lam "f" (Lam "t" (Var "f"))) (TyVar "<?>")]
+      outputs
+        `shouldBe` [ Evaluated
+                       (Abs ["f", "t"] (Sym "f"))
+                       (Lam "f" (Lam "t" (Var "f")))
+                       (TyVar "<?>")
+                   ]
 
     around withTempFile $
       it "evaluates single MiniLang term read from IO" $ \fileName -> do