Re: recursive nested functions

nojb <nojb@uchicago.edu> writes:
> I'm writing a compiler for a language that admits recursive nested
> functions and I am stuck trying to figure out how to handle them. My
> objective is to lift all nested functions to top level and pass all
> their free variables explicitly as parameters. For this, I have to
> figure out which variables are free. So when I'm analyzing the body
> of each function, I record its free variables. But then obviously when
> I come across a function call, I have to add _its_ free variables to
> the list of the enclosing function. You can see how this will loop
> endlesly if we allow recursive functions...


It won't loop endlessly, there is a fixed upper bound, a function f()
with a finite set of free variables: v1, v2, ... will not introduce
any new free variables when it calls itself recursively (even
indirectly). Thus, when you take the closure, it is a closed finite
set that is bounded by the union of free variables of the consituent
functions.


Hope this helps,
-Chris


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Chris Clark email: christopher.f.clark@compiler-resources.com
Compiler Resources, Inc. Web Site: http://world.std.com/~compres
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Berlin, MA 01503 USA twitter: @intel_chris
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