Tehee

3or4/Interpreter/Self.hs

@@ -0,0 +1,42 @@
+{-# Language LambdaCase, Strict #-}
+
+module Interpreter.Self where
+
+import Chi
+import Interpreter.Haskell
+
+mapExp :: Exp
+mapExp = parse
+  "\\f. rec map = \\xs. case xs of \
+  \ { Nil() -> Nil() \
+  \ ; Cons(x,xs) -> Cons(f x, map xs)\
+  \ }"
+
+substBrExp :: Exp
+substBrExp = parse
+  "rec substBr = \\x. "
+
+ifExp :: Exp
+ifExp = parse
+  "\\b. \\t. \\f. case b of \
+  \ { True() -> t \
+  \ ; False() -> f \
+  \ }"
+
+equalExp :: Exp
+equalExp = parse ""
+
+substExp :: Exp
+substExp =
+  subst (Variable "if") ifExp .
+  subst (Variable "equal") equalExp .
+  subst (Variable "substBr") substBrExp .
+  subst (Variable "map") mapExp $ parse
+        "\\var. \\e. rec subst = \\x. case x of\
+        \ { Apply(e1,e2) -> Apply(subst e1, subst e2) \
+        \ ; Lambda(x,y) -> if (equal x var) Lambda(x,y) Lambda(x,subst y) \
+        \ ; Var(x) -> if (equal x var) e Var(x) \
+        \ ; Const(c,es) -> Const(c, map subst es) \
+        \ ; Rec(x, e') -> if (equal x var) Rec(x,e') Rec(x,subst e')\
+        \ ; Case(e',bs) -> _ \
+        \ }"