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Groups > comp.lang.forth > #3608

Re: macro expansion ?

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On 2011-06-28 18:51:51 +0100, Chris Hinsley said:

> On 2011-06-28 18:34:06 +0100, Chris Hinsley said:
> 
>>>> 
>>>> But this led me on to thinking how would I do a more Lisp like macro ?
>>>> Somthing that would be expanded and then that expantion expanded till
>>>> there was no more expantions.
>>> 
>>> I think that's going to happen anyway.  When EVALUATE comes across a
>>> MACRO it'll expand it recursively.
>>> 
>>> Perhaps you could show us an example of something like this not
>>> working.
>>> 
>>> Andrew.
>> 
>> A simple example that does work as intended.
>> 
>> macro ma * +"
>> macro mp1 1 -rot ma"
>> : t1 1 -rot * + ;
>> : t2 mp1 ;
>> 
>> Both t1 and t2 dissesemble to exactly the same code. Good that's as I 
>> intended. And show the expansion of macros is recursive. :)
>> 
>> However now I'm thinking how would a do a macro that can use itself ? 
>> Part of this is no problem, the EVALUATE call will be able to find the 
>> named macro and recurse in no problem.
>> 
>> macro bert bert"
>> 
>> Would just recurse till it crashed. But there's no problem with defineing it.
>> 
>> So how would I exit a macro expansion ? I'd presumably have to have 
>> interpret time, rather than runtime conditions used in the macro ?
>> 
>> Forgive me if I'm rambling a bit, I'm making this up on the fly here, 
>> trying to see if I can spot a problem. Would I hit a problem that IF, 
>> ELSE, ENDIF are only available as compile time words (well they are for 
>> my Forth, I know others have made them work at interpret time). Maybe 
>> you just stick to useing [IF], [ELSE], [THEN] in macro definitions and 
>> it will all just work (tm).
>> 
>> I'll try a few more experiments.
>> 
>> Chris
> 
> OK, somthing definate as an example I'd like to see work.
> 
> Lets say I have a Forth Hakiu pixel shader, it defines a word that 
> takes x,y and gives back an ARGB. Normally I call this each pixel at 
> runtime to generate a pixel on the fly, either in a shader on the GPU 
> or with a peice of code that creates a texture at runtime.
> 
> However, maybe I'd like to create a macro that uses the Haiku to create 
> an embeded version of the texture as read only data stored as a word 
> that returned a pointer to the embeded array of pixels ? All the 
> processing of the pixels is to be done at compile time, no runtime 
> overhead. Can I create a _macro_ that expands into the ARGB data array 
> given a Hauku name and resolution value at compile time ?
> 
> I'm just throwing this out as an example, I've not actualy tried to do 
> it yet, but it might show up a problem. I can see that you could define 
> a word that is an IMMEDIATE word to do this job at compile time, but 
> can you do it with the/a macro concept ?
> 
> Chris

How about a macro that did greatest common divider ?

Function gcd(a As Integer, b As Integer) As Integer
If b = 0 Then
gcd = a
Else
gcd = gcd(b,a)
End If
End Function

Chris

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Thread

macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 14:43 +0100
  Re: macro expansion ? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2011-06-28 10:58 -0500
    Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 18:34 +0100
      Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 18:51 +0100
        Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 19:02 +0100
          Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 19:11 +0100
            Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 19:17 +0100
              Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 19:47 +0100
                Re: macro expansion ? Josh Grams <josh@qualdan.com> - 2011-06-29 15:34 +0000
                Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-29 19:21 +0100
            Re: macro expansion ? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2011-06-29 03:15 -0500
              Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-29 13:11 +0100
            Re: macro expansion ? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2011-06-29 17:17 +0100
              Re: macro expansion ? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2011-06-29 18:09 +0100
                Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-29 19:32 +0100
                Re: macro expansion ? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2011-07-02 08:48 +0100
    Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-29 00:44 +0100
    Re: macro expansion ? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2011-06-29 20:39 +0100
  Re: macro expansion ? Elizabeth D Rather <erather@forth.com> - 2011-06-28 08:59 -1000
    Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 20:39 +0100
      Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-28 21:34 +0100
        Re: macro expansion ? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2011-06-29 03:26 -0500
  Re: macro expansion ? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-06-29 11:25 +0000
    Re: macro expansion ? Chris Hinsley <chris.hinsley@gmail.com> - 2011-06-29 13:24 +0100
      Re: macro expansion ? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-07-03 14:02 +0000
    Re: macro expansion ? Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-06-29 18:48 +0000
  Re: macro expansion ? BruceMcF <agila61@netscape.net> - 2011-06-30 11:11 -0700
  Re: macro expansion ? Ian Osgood <iano@quirkster.com> - 2011-07-02 16:22 -0700
  Re: macro expansion ? Hugh Aguilar <hughaguilar96@yahoo.com> - 2011-07-05 17:35 -0700

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