John Cowan <co...@mercury.ccil.org> writes: > Jim Wise scripsit: > >> Are there plans to include explicit pattern matching operations, such as >> Common Lisp's DESTRUCTURING-BIND or Racket's match[1]? > > We don't work in terms of plans, but in terms of proposals, and right now > there are no concrete proposals. If you put together a concrete proposal > (doesn't have to be detailed, just clear) and send it to me, I will be > happy to post it for WG consideration.
I'd be willing to cull the list discussion as a proposal, if there seems
to be a common thread. Are there any details on what's wanted in such a
proposal? Or just the discussion on the list? Any standard formatting?
FWIW, racket provides the following in its racket/match library:
(match <val>
(<pattern> <body>)
...)
(match* (<val> ...)
((<pattern> ...) <body>)
...)
and derivative forms
(match-lambda (<pattern> <body>) ...)
(match-lambda* (<pattern> <body>) ...)
(match-let ((<pattern> <expr>) ...)
which are equivalent to
(lambda (x) (match x (<pattern> <body>) ...)
(lambda l (match l (<pattern> <body>) ...)
((lambda (x ...) (match* (x ...) (<pattern> <body>) ...))
<expr> ...)
and
(match-let* ((<pattern> <expr>) ...)
(match-letrec ((<pattern> <expr>) ...)
Optionally, a second module could re-export match-lambda* as `lambda',
though I'm not sure is needed (it should certainly be possible to use
the matching module without getting this).
Common Lisp's DESTRUCTURING-BIND is provided here by match-let.
What pattern matching capabilities do other Scheme(-like)s provide?
--
Jim Wise
jw...@draga.com
pgpYJtVJcGFO3.pgp
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