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Re: Allow Scheme functions to be called inside of markup (issue 28507004

From: thomasmorley65
Subject: Re: Allow Scheme functions to be called inside of markup (issue 285070043 by address@hidden)
Date: Sat, 16 Jan 2016 21:19:08 +0000

On 2016/01/16 20:37:23, dak wrote:
On 2016/01/16 19:54:54, thomasmorley651 wrote:
> After some testings I'm quite happy with it, apart from one use
> fooII =
> #(define-scheme-function (arg)(markup-list?)
> #{
>   \markup \column $arg
> #})
> %% doesn't work:
> \markup \line { "xy" \fooII { "does" "not" "work"} }
> %% works
> \markup \line { "xy" \fooII \markuplist { "whatever" "else" } }
> \markup \line { "xy" \fooII #'("whatever" "else") }
> I think I know why the first case doesn't work. Though, I have no
good idea
> to explain it in the docs without telling a very technical story,
likely very
> confusing to the average-user.
> Additionally, having to add \markuplist as in the second example is
not nice.
> Only a little better is the need to revert to scheme as done in the
> example.
> What other problematic cases can you predict deductively?

Sigh.  This looks like a can of worms.

Arguments of type markup?/markup-list? will obviously be problematic
(apart from
the trivial case of strings) without explicit \markup/\markuplist.  I
am afraid
that one would need to teach markup-mode internal arguments to generic
argument lists.  That would appear to be a likely user expectation.

Agreed. Users would be surprised to find the following not working:

fooVI = #(define-scheme-function (arg)(markup?) arg)
\markup \line { "xy" \fooVI \with-color #red "bla" }

However, `{' and `}' are mode-independent, and so { } already stands
for an
empty sequential music expression and making it stand at the same time
for an
empty markup list...  Ugh.

So much for the triviality of the change.

Well, it would be some syntactic sugar. No real need for it.
Bury it?

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