i have no strong feelings about that either way, however since in haskell we do not have "let" vs "let rec" distinctions, perhaps we should not have "do" vs "do rec" distinction. this of course would break programs relying on shadowing (and at least i write quite a few of those, but that is mostly habit). i doubt that this will cause many backward compatability problems, as one can compile old modules (not using recursive do) without the flag enabling recursive dos.
bye iavor
Simon Peyton-Jones wrote:
I agree with this. We'll move GHC to implement any consensus.
My own opinion is that expr :: = ... | do { stmts }
stmts :: = .. | rec { stmts }
is the cleanest story. I guess that we should ensure that
do rec { stmts }
means what it looks like.
Simon
| -----Original Message-----
| From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of
| [EMAIL PROTECTED]
| Sent: 16 September 2003 18:09
| To: [EMAIL PROTECTED]
| Subject: Syntax extensions: mdo and do...rec
| | Dear Haskellers,
| | A questions.
| | The do-notation has been extended to support recursive bindings by
using
| the "mdo" keyword. The do-notation has also been extended (through
Ross
| Patterson's preprocessor, and now also GHC) to support programming
| with arrows. In that context, a different syntax, using the keyword
"rec",
| is used to enable recursive bindings.
| | It seems somewhat confusing to have distinct syntax for what appears
| to be very closely related purposes. Would it be possible have just a
| single syntactic extension to enable recursive bindings in either
context?
| (Presumably the "rec" version is a bit more flexible in that it can be
| applied to a subset of the bindings in a do-construct.)
| | Best regards,
| | /Henrik
| | --
| Henrik Nilsson
| Yale University
| Department of Computer Science
| [EMAIL PROTECTED]
| _______________________________________________
| Haskell mailing list
| [EMAIL PROTECTED]
| http://www.haskell.org/mailman/listinfo/haskell
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-- ================================================== | Iavor S. Diatchki, Ph.D. student | | Department of Computer Science and Engineering | | School of OGI at OHSU | | http://www.cse.ogi.edu/~diatchki | ==================================================
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