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Date: -- (:)
From: Jon Harrop <jon@f...>
Subject: Re: [Caml-list] Patterns that evaluate
On Tuesday 13 February 2007 22:04, Jacques Carette wrote:
> I recently wrote some ocaml code which "worked", but not as I
> intended...  The test cases I tried worked, but I should have tested
> harder.  Apparently I was under the mistaken impression that OCaml's
> pattern-matching was more "first class"!  So I wrote (in part):
>
> let buildsimp cast e f1 f2 = fun e1 -> fun e2 -> match (e1,e2) with
>
>                                                  | ({st = Some e}, _) -> e2
>
> and I expected it to work.  Only a code review by a colleague 'found'
> this bug in my code.
>
> Question: would it be a difficult extension?  This seemed so "natural",
> I just "used" the feature before it was quite there yet ;-).

F# just introduced active patterns, which does what you want AFAIK. Of course, 
you must disambiguate that from the OCaml's current interpretation of the 
above (binding "e").

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists