== matchertext

[[toc:]]

== Description

''matchertext'' is a "syntactic discipline" that allows for cross-language
embedding of source code. It was invented by Bryan Ford (who also invented
parsing expression grammars and packrat parsing). To learn more, see Ford's
[[https://bford.info/pub/lang/matchertext/|introductory blog post]], and his
[[https://arxiv.org/abs/2212.14129|more substantial paper]]. Briefly (quote from
the blog post),

 The pragmatic essence of the matchertext idea is simple. First, we define six
 particular ASCII characters as matchers: namely the open and close parentheses
 (), the square brackets [], and the curly braces {}. We call these characters
 matchers because their traditional, already-ubiquitous purpose is to be used in
 matching pairs to surround and delimit other text.
 
 Now we define matchertext as any plain text string conforming to one additional
 rule or “syntactic discipline”: namely that matchers must match, throughout any
 matchertext string, without exception. Nesting is allowed, but must use
 corresponding matchers. For example, the string ‘([{foo}])’ is valid
 matchertext, but strings like ‘(foo’, ‘bar}’, or ‘(]’ are not matchertext.

The matchertext egg extends the Scheme language to be able to host matchertext
in string literals.

== Syntax

<syntax>#m{MATCHERTEXT}</syntax>

This is a string literal, where {{MATCHERTEXT}} is valid matchertext; no need to
escape any characters as long as matchers match.

== Examples

To run the examples, don't forget to

<enscript highlight="scheme">
(import matchertext)
</enscript>

=== Simple usage

<enscript highlight="scheme">
(string=? "hello, world" #m{hello, world}) ; #t
</enscript>

<enscript highlight="scheme">
(string=? "#[{(##)}]\\\\(\\)[]#[{\"}]" #m{#[{(##)}]\\(\)[]#[{"}]}) ; #t
</enscript>

Let's try to print the code of the above example.

<enscript highlight="scheme">
(display #m{(string=? "#[{(##)}]\\\\(\\)[]#[{\"}]" #m{#[{(##)}]\\(\)[]#[{"}]}) ; #t})
</enscript>

== Author

[[/users/hernan-ibarra-mejia|Hernán Ibarra Mejia]]

== Repository

Development happens in [[https://git.sr.ht/~nagbu/matchertext|SourceHut]].

== Requirements

None (but testing requires the [[test|test egg]]).

== Version history

; 1.0 : Initial release.

== License

[[https://git.sr.ht/~nagbu/matchertext/blob/main/COPYING|GPLv3]].