From: Bakul Shah <bakul@iitbombay.org>
To: Rob Pike <robpike@gmail.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] Regular Expressions
Date: Fri, 31 Jul 2020 18:31:39 -0700 [thread overview]
Message-ID: <3D47666B-BF70-4810-9D43-CAE16E44F25D@iitbombay.org> (raw)
In-Reply-To: <CAKzdPgygJAwzzEKOMkdo0bqrNUKaO8xzTm0h_nXVgQ9=t7k7kA@mail.gmail.com>
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I was trying to get Will to try simple stuff out himself from first principles (to get started) but this is of course far better!
> On Jul 31, 2020, at 5:36 PM, Rob Pike <robpike@gmail.com> wrote:
>
> I think this link - https://swtch.com/~rsc/regexp/regexp1.html <https://swtch.com/~rsc/regexp/regexp1.html> i- s the best place to start. Superb exposition on the background, theory, and implementation as well as a bit of history of how the industry lost its way with regular expressions.
>
> Regular expressions are beautiful, simple, and widely misunderstood.
>
> -rob
>
>
> On Sat, Aug 1, 2020 at 10:03 AM Bakul Shah <bakul@iitbombay.org <mailto:bakul@iitbombay.org>> wrote:
> On Jul 31, 2020, at 3:57 PM, Will Senn <will.senn@gmail.com <mailto:will.senn@gmail.com>> wrote:
> >
> > I've always been intrigued with regexes. When I was first exposed to them, I was mystified and lost in the greediness of matches. Now, I use them regularly, but still have trouble using them. I think it is because I don't really understand how they work.
> > ...
> > 1. What's the provenance of regex in unix (when did it appear, in what form, etc)?
> > 2. What are the 'best' implementations throughout unix (keep it pre 1980s)?
> > 3. What are some of the milestones along the way (major changes, forks, disagreements)?
> > 4. Where, in the source, or in a paper, would you point someone to wanting to better understand the mechanics of regex?
>
> Start here: https://en.wikipedia.org/wiki/Thompson%27s_construction <https://en.wikipedia.org/wiki/Thompson%27s_construction>
>
> [I learned about regular expressions in an automata theory class,
> before I knew anything about Unix. What helped me was learning
> about finite state machines. You won't need more than paper and
> pencil to construct one. Reading source code would make more
> sense once you grasp how to construct a FSM corresponding to a RE.]
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next prev parent reply other threads:[~2020-08-01 1:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-31 22:57 Will Senn
2020-08-01 0:01 ` Bakul Shah
2020-08-01 0:36 ` Rob Pike
2020-08-01 0:53 ` John P. Linderman
2020-08-01 1:31 ` Bakul Shah [this message]
2020-08-01 1:39 ` Larry McVoy
2020-08-01 2:33 ` Will Senn
2020-08-01 2:50 ` Rich Morin
2020-08-01 3:01 ` Larry McVoy
2020-08-01 3:07 ` Will Senn
2020-08-01 4:31 ` Earl Baugh
2020-08-01 4:53 ` ron minnich
2020-08-01 5:48 ` Andrew Hume
2020-08-01 13:31 ` Richard Salz
2020-08-01 13:43 ` Andrew Hume
2020-08-02 0:45 ` Christopher Browne
2020-08-09 1:00 ` Dave Horsfall
2020-08-09 1:15 ` Nelson H. F. Beebe
2020-08-09 23:53 ` Dave Horsfall
2020-08-10 1:38 ` John Cowan
2020-08-01 0:00 Noel Chiappa
2020-08-01 21:12 Doug McIlroy
2020-08-09 23:44 ` Dave Horsfall
2020-08-10 0:50 ` Rob Pike
2020-08-02 4:59 Rudi Blom
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