m4_curry [was: naming m4_transform]

[Eric Blake]

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According to Eric Blake on 10/14/2008 5:31 PM:
> But m4 doesn't make it easy to write anonymous functions.  By making 
> m4_map_args supply the ( and ) around a single argument, I no longer have a 
> way 
> to inject $2 and $3 into the mapping function, at least, not without some 
> inefficiencies.  I've thought about something like this (untested, and I'm 
> not 
> even sure I'm using the best naming convention):

I double checked wikipedia, and this is the right name:
http://en.wikipedia.org/wiki/Currying

> 
> # m4_curry(MACRO, ARG...)
> # -----------------------
> # Can be used as a currying macro - the expansion of this macro expects
> # to be expanded as another macro that takes one argument, which is then
> # appended to the list of ARGs and passed to the invocation of MACRO.
> # For example,
> #   m4_curry([m4_do], [1], [2])([3])
> # is identical to
> #   m4_do([1], [2], [3])
> m4_define([m4_curry], [$1(m4_shift($@), _$0])
> m4_define([_m4_curry],                     [[$1])])

and I got it right - subsequent testing confirmed that what I doodled in
the email is the right implementation!

m4_curry([m4_curry], [m4_reverse], [1])([2])([3])
=> 3, 2, 1

so I'll be adding m4_curry to m4sugar, whether or not it ends up making a
more efficient alternative to autoconf's use of m4_foreach_w.  I just have
to finish the testsuite addition and post the patch for review first.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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