lambda-calculator 0.5.0 → 1.0.0

raw patch · 3 files changed

+36/−1 lines, 3 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• lambda-calculator.cabal +1/−1
• src/Language/Lambda/Eval.hs +13/−0
• test/Language/Lambda/EvalSpec.hs +22/−0

@@ -1,5 +1,5 @@ name:                lambda-calculator-version:             0.5.0+version:             1.0.0 synopsis:            A lambda calculus interpreter description:         Please see README.md homepage:            https://github.com/sgillespie/lambda-calculus#readme

@@ -25,6 +25,19 @@   where uniq = fromMaybe name (find (`notElem` freeVars) uniqs) alphaConvert _ _ e = e +etaConvert :: Eq n => LambdaExpr n -> LambdaExpr n+etaConvert (Abs n (App e1 (Var n')))+  | n == n'   = etaConvert e1+  | otherwise = Abs n (App (etaConvert e1) (Var n'))+etaConvert (Abs n e@(Abs _ _)) +  -- If `etaConvert e == e` then etaConverting it will create an infinite loop+  | e == e'   = Abs n e'+  | otherwise = etaConvert (Abs n e')+  where e' = etaConvert e+etaConvert (Abs n expr) = Abs n (etaConvert expr)+etaConvert (App e1 e2)  = App (etaConvert e1) (etaConvert e2)+etaConvert expr@(Var _) = expr+ sub :: Eq n => n -> LambdaExpr n -> LambdaExpr n -> LambdaExpr n sub name b@(Var name') expr   | name == name' = expr

@@ -74,6 +74,28 @@           uniques = ["x", "y"]       alphaConvert uniques freeVars expr `shouldBe` Abs "y" (Var "y") +  describe "etaConvert" $ do+    it "eta converts simple expressions" $ do+      let expr = Abs "x" $ App (Var "f") (Var "x")+      etaConvert expr `shouldBe` Var "f" ++    it "eta converts nested applications" $ do+      let expr = Abs "y" $ App (App (Var "f") (Var "x")) (Var "y")+      etaConvert expr `shouldBe` App (Var "f") (Var "x")++      let expr' = Abs "x" $ Abs "y" (App (App (Var "f") (Var "x")) (Var "y"))+      etaConvert expr' `shouldBe` Var "f" ++      let expr'' = Abs "x" (Abs "y" (App (Var "y") (Var "x")))+      etaConvert expr'' `shouldBe` expr''++      let expr''' = Abs "f" (Abs "x" (Var "x"))+      etaConvert expr''' `shouldBe` expr'''++    it "ignores non-eta convertable expressions" $ do+      let expr = Abs "x" $ Var "x"+      etaConvert expr `shouldBe` expr+   describe "freeVarsOf" $ do     it "Returns simple vars" $ do       freeVarsOf (Var "x") `shouldBe` ["x"]