[CM] Help sought for a macro

[Christos Vagias]

Hi Iain,

Wasn't aware of the chain srfi. Interesting.
Since I'm coming more from clojure I guess I'll focus a bit more on the
"as->", "->" and "->>".
Could try fiddling with these from Monday on and will keep you posted on
the process.

The "(x ~> a _ b ~> c _ )" form seems kinda too much though, adding infix
notation to the mix

On Sat, 19 Sep 2020 at 19:37, Iain Duncan <iainduncanlists at gmail.com> wrote:

> Hi colleagues, I'm trying to figure out how to build a couple of threading
> macros that would be very helpful in Max/MSP for Scheme for Max, but it is
> frankly over my head right now. Working it out will be a good exercise but
> I figured I would post here in case this is trivial for some macro experts
> in S7 and they are willing to share something I can study.
>
> I want to implement something like srfi-197, where it is called "chain".
> (but srfi-197 uses syntax-case and syntax-rules)
>
> so from the docs there:
>
> (chain x (a b _)) ; => (a b x)
> (chain (a b) (c _ d) (e f _)) ; => (let* ((x (a b)) (x (c x d))) (e f x))
> (chain (a) (b _ _) (c _)) ; => (let*-values (((x1 x2) (a)) ((x) (b x1 x2))) (c x))
>
>
> But what I'd really to make on top of that is a version for allows one to
> use this for one liners in Max without inner parens, so something like
> this, where the macro is ~>
>
> (x ~> a _ b ~> c _ )
> becomes something  equivalent of:
> (c (a (eval x) b))
>
> Because Scheme for Max will take a max message and treat it as code to be
> wrapped in outer parens and then eval'd, this will let people do very
> useful things in one short max message (where say $i and $i2 come from
> another max message sending to it:
>
> $i1 ~> + 10 _ ~> / $i2 _
>
> If anyone has suggestions or feels like helping that would be amazing.
> thanks!
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