17 May
2020
17 May
'20
7:36 a.m.
It looks like only grap and pic have mkfiles that invoke lex.
On May 16, 2020, at 9:23 PM, Warner Losh
<imp(a)bsdimp.com> wrote:
On Sat, May 16, 2020, 6:05 PM Brantley Coile <brantley(a)coraid.com> wrote:
“The asteroid to kill this dinosaur is still in orbit.“
—- Plan 9 lex man page
I always hand craft my lexers and use yacc to parse. Most code on plan 9 does that as
well.
Wow! That is the most awesome thing I've seen in a while....
Warner
Brantley
> On May 16, 2020, at 8:00 PM, Jon Steinhart <jon(a)fourwinds.com> wrote:
>
> Steffen Nurpmeso writes:
>> Tony Finch wrote in
>> <alpine.DEB.2.20.2005142316170.3374(a)grey.csi.cam.ac.uk>:
>> |Larry McVoy <lm(a)mcvoy.com> wrote:
>> |>
>> |> It's got some perl goodness, regexps are part of the syntax, ....
>> |
>> |I got into Unix after perl and I've used it a lot. Back in the 1990s I
saw
>> |Henry Spencer's joke that perl was the Swiss Army Chainsaw of Unix, as a
>> |riff on lex being its Swiss Army Knife. I came to appreciate lex
>> |regrettably late: lex makes it remarkably easy to chew through a huge pile
>> |of text and feed the pieces to some library code written in C. I've been
>> |using re2c recently (http://re2c.org/) which is differently weird than
>> |lex, though it still uses YY in all its variable names. It's remarkable
>> |how much newer lexer/parser generators can't escape from the user
>> |interface of lex/yacc. Another YY example: http://www.hwaci.com/sw/lemon/
>>
>> P.S.: i really hate automated lexers. I never ever got used to
>> use them. For learning i once tried to use flex/bison, but
>> i failed really hard. I like that blood, sweat and tears thing,
>> and using a lexer seems so shattered, all the pieces. And i find
>> them really hard to read.
>>
>> If you can deal with them they are surely a relief, especially in
>> rapidly moving syntax situations. But if i look at settled source
>> code which uses it, for example usr.sbin/ospfd/parse.y, or
>> usr.sbin/smtpd/parse.y, both of OpenBSD, then i feel lost and am
>> happy that i do not need to maintain that code.
>>
>> --steffen
>
> Wow, I've had the opposite experience. I find lex/yacc/flex/bison really
> easy to use. The issue, which I believe was covered in the early docs,
> is that some languages are not designed with regularity in mind which makes
> for ugly code. But to be fair, that code is at least as ugly with hand-crafted
> code.
>
> I believe that the original wisecrack was directed towards FORTRAN. My ancient
> experience was that it was using lex/yacc for HSPICE was not going to work so I
> had to hand-craft code for that.
>
> Jon