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[Caml-list] fixpoint
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Date: 2002-08-04 (05:04)
From: John Max Skaller <skaller@o...>
Subject: Re: [Caml-list] fixpoint
John Max Skaller wrote:


> which suggests the following reduction:
>    fix f . fun x . e ==> fix z . e [f x -> z]
> Well, the rule works in this case. Will it always work?
I meant:

    fix f. fun x . e ==> fun x. fix z . e [f x -> z] (* z not occuring 
in e *)

ie. the fix and fun binders swap around with the substitution.
I should also have noted that obviously this only works if it is
done at the right time, eg in

    fix g. (fun x (fun f ( f x) g) x)

the inner redex must be reduced first.

John Max Skaller,
snail:10/1 Toxteth Rd, Glebe, NSW 2037, Australia.

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