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From: Kaz Kylheku <643-408-1753@kylheku.com>
Newsgroups: comp.unix.shell,comp.unix.programmer,comp.lang.misc
Subject: Re: Command Languages Versus Programming Languages
Date: Thu, 21 Nov 2024 19:12:03 -0000 (UTC)
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On 2024-11-20, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
> On 20.11.2024 09:21, Muttley@DastartdlyHQ.org wrote:
>> Regex itself is clumsy beyond simple search and replace patterns. A lot of
>> stuff I've seen done in regex would have better done procedurally at the
>> expense of slightly more code but a LOT more readability. Also given its
>> effectively a compact language with its own grammar and syntax IMO it should
>> not be the core part of any language as it can lead to a syntatic mess, which 
>> is what often happens with Perl.
>
> I wouldn't look at it that way. I've seen Regexps as part of languages
> usually in well defined syntactical contexts. For example, like strings
> are enclosed in "...", Regexps could be seen within /.../ delimiters.
> GNU Awk (in recent versions) went towards first class "strongly typed"
> Regexps which are then denoted by the @/.../ syntax.

These features solve the problem of regexes being stored as character
strings not being recognized by the language compiler and then having
to be compiled at run-time.

They don't solve all the ergonomics of regexes that Muttley is talking
about.

> I'm curious what you mean by Regexps presented in a "procedural" form.
> Can you give some examples?

Here is an example: using a regex match to capture a C comment /* ... */
in Lex compared to just recognizing the start sequence /* and handling
the discarding of the comment in the action.

Without non-greedy repetition matching, the regex for a C comment is
quite obtuse. The procedural handling is straightforward: read
characters until you see a * immediately followed by a /.

In the wild, you see regexes being used for all sorts of stupid stuff,
like checking whether numeric input is in a certain range, rather than
converting it to a number and doing an arithmetic check.

-- 
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca