59 lines
1.6 KiB
Haskell
59 lines
1.6 KiB
Haskell
{-# Language LambdaCase, Strict #-}
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module Interpreter.Self where
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import Chi
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import Interpreter.Haskell
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mapExp :: Exp
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mapExp = parse
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"\\f. rec map = \\xs. case xs of \
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\ { Nil() -> Nil() \
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\ ; Cons(x,xs) -> Cons(f x, map xs)\
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\ }"
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ifExp :: Exp
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ifExp = parse
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"\\b. \\t. \\f. case b of \
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\ { True() -> t \
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\ ; False() -> f \
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\ }"
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equalExp :: Exp
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equalExp = parse
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"rec equal = \\m. \\n. case m of \
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\ { Zero() -> case n of { Zero() -> True(); Suc(n) -> False() } \
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\ ; Suc(m) -> case n of { Zero() -> False(); Suc(n) -> equal m n }\
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\ }"
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elemExp :: Exp
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elemExp =
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subst (Variable "equal") equalExp .
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subst (Variable "if") ifExp $ parse
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"\\x. rec elem = \\l. case l of \
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\ { Nil() -> False() \
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\ ; Cons(v,vs) -> if (equal x v) True() (elem vs)\
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\ }"
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substBrExp :: Exp
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substBrExp =
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subst (Variable "elem") elemExp $ parse
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"\\subst. \\var. \\b. case b of \
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\ { Branch(c,vs,e') -> if (elem var vs) Branch(c,vs,e') Branch(c,vs, subst e') \
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\ }"
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substExp :: Exp
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substExp =
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subst (Variable "if") ifExp .
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subst (Variable "equal") equalExp .
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subst (Variable "substBr") substBrExp .
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subst (Variable "map") mapExp $ parse
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"\\var. \\e. rec subst = \\x. case x of\
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\ { Apply(e1,e2) -> Apply(subst e1, subst e2) \
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\ ; Lambda(x,y) -> if (equal x var) Lambda(x,y) Lambda(x,subst y) \
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\ ; Var(x) -> if (equal x var) e Var(x) \
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\ ; Const(c,es) -> Const(c, map subst es) \
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\ ; Rec(x, e') -> if (equal x var) Rec(x,e') Rec(x,subst e')\
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\ ; Case(e',bs) -> Case(subst e', map (substBr subst var) bs) \
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\ }"
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