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From: allen@sbcs.sunysb.edu ( Allen Leung)
Newsgroups: comp.object,comp.lang.c++
Subject: Re: Continuations
Message-ID: <4109@sbcs.sunysb.edu>
Date: 1 Dec 89 19:59:01 GMT
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In article <10008@june.cs.washington.edu>, peterd@cs.washington.edu (Peter C. Damron) writes:
> 4. C and C++ have first class functions.  Functions can be passed as
>    parameters, returned as function values, and assigned to variables.
>    The reason that C and C++ do not allow nested functions is precisely
>    so that they can have first-class functions implemented on a stack
>    (e.g. no closure required).  The "parent block" of a function is
>    simply the global variables.
> 
> Peter.
> peterd@cs.washington.edu
> {ucbvax,decvax,etc.}!uw-beaver!uw-june!peterd


I must disagree.
C and C++ definitely *don't* have first class functions.  From
a function programming view point, type alpha is first class means that
values of alpha enjoy all the privilages granted to first class types.
In terms of C this means you are supposed to be able to do things like 
this with functions:

      int(*)() foo( int y; )
      {
         int x;                  // if you can local declare int/float/* ....etc
         float r;
         char *a;
         
         int bar( int z )        // you should be able to local declare bar
         {  return y + z; }      // y is free in bar but bound in foo
       
         return bar;     
      }

--Allen
allen@sbcs.sunysb.edu


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