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(* Title: MiniML.thy


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Author: Thomas Stauner


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Copyright 1995 TU Muenchen


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Recursive definition of type inference algorithm I for Mini_ML.


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*)


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I = W +


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consts

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I :: [expr, type_expr list, nat, subst] => result_W

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primrec I expr


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I_Var "I (Var i) a n s = (if i < length a then Ok(s, nth i a, n)


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else Fail)"


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I_Abs "I (Abs e) a n s = I e ((TVar n)#a) (Suc n) s bind


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(%(s,t,m). Ok(s, Fun (TVar n) t, m) )"


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I_App "I (App e1 e2) a n s =


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I e1 a n s bind


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(%(s1,t1,m1). I e2 a m1 s1 bind


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(%(s2,t2,m2). mgu ($s2 t1) (Fun ($s2 t2) (TVar m2)) bind


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(%u. Ok($u o s2, TVar m2, Suc m2) ) ))"


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end
