Re: Representing Closures in C

haberg@math.su.se (Hans Aberg)
23 Jul 2006 16:19:26 -0400

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Representing Closures in C johan.tibell@gmail.com (Johan Tibell) (2006-07-21)
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From: haberg@math.su.se (Hans Aberg)
Newsgroups: comp.compilers
Date: 23 Jul 2006 16:19:26 -0400
Organization: Mathematics
References: 06-07-058
Keywords: functional
Posted-Date: 23 Jul 2006 16:19:26 EDT

<johan.tibell@gmail.com> wrote:


> I did quick search for "de Bruin index" but it came back empty. What is
> a "de Bruin index"?


One replaces the variable names in a lambda-expressions with a
non-negative integer: in each occurrence, the number of intermediate
lambda-heads between the lambda-head that the variable is bound to,
and the variable occurrence itself. The point is that variable
substitution needs no variable relabeling.


However an elegant method, I am told that it hard to use in debugging,
as it is difficult for humans to interpret. So in actual functional
language implementations, it has not been used so much.


--
    Hans Aberg


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