Explicit local bindings for let/where

test/Spec.hs

@@ -336,7 +336,7 @@ parser = testGroup "Parser Tests"
 
   , testCase "Parse let expression" $ do
       let input  = "let x = t t in x"
-          expect = SApp (SLambda ["x"] (SVar "x" Nothing)) (SApp TLeaf TLeaf)
+          expect = SLet "x" (SApp TLeaf TLeaf) (SVar "x" Nothing)
       parseSingle input @?= expect
 
   , testCase "Evaluate let expression" $ do
@@ -344,18 +344,36 @@ parser = testGroup "Parser Tests"
 
   , testCase "Parse let function binding" $ do
       let input  = "let f x = x in f t"
-          expect = SApp (SLambda ["f"] (SApp (SVar "f" Nothing) TLeaf))
-                        (SLambda ["x"] (SVar "x" Nothing))
+          expect = SLet "f" (SLambda ["x"] (SVar "x" Nothing))
+                        (SApp (SVar "f" Nothing) TLeaf)
       parseSingle input @?= expect
 
   , testCase "Parse where expression" $ do
       let input  = "x where x = t t"
-          expect = SApp (SLambda ["x"] (SVar "x" Nothing)) (SApp TLeaf TLeaf)
+          expect = SLet "x" (SApp TLeaf TLeaf) (SVar "x" Nothing)
       parseSingle input @?= expect
 
   , testCase "Evaluate where expression" $ do
       tricuTestString "x where x = 1" @?= "Fork (Stem Leaf) Leaf"
 
+  , testCase "Parse where binding with arguments (SLet)" $ do
+      let input  = "f 3 where f x = x"
+          expect = SLet "f" (SLambda ["x"] (SVar "x" Nothing))
+                        (SApp (SVar "f" Nothing) (SInt 3))
+      parseSingle input @?= expect
+
+  , testCase "Evaluate where binding with arguments matches applied lambda" $ do
+      tricuTestString "f (t t) where f x = t x x"
+        @?= tricuTestString "(f : f (t t)) (x : t x x)"
+
+  , testCase "Evaluate nested let bindings" $ do
+      tricuTestString "let a = t t in let b = t in t a b"
+        @?= tricuTestString "t (t t) t"
+
+  , testCase "Inner let binding shadows outer binding" $ do
+      tricuTestString "let x = t in let x = t t in x"
+        @?= tricuTestString "t t"
+
   , testCase "Parse indented multiline definition body" $ do
       let input  = "x =\n  t\n    t"
           expect = SDef "x" [] (SApp TLeaf TLeaf)