RE: Re: [Haskell] Proposal: Allow "\=" for field update in record update syntax
"Simon Peyton-Jones" <[email protected]> Mon, 7 Mar 2005 08:39:03 -0000
| Newsgroups | gmane.comp.lang.haskell.template |
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| Message-ID | <036EAC76E7F5EC4996A3B3C3657D411601DBE7DD@EUR-MSG-21.europe.corp.microsoft.com> |
What exactly is it that TH doesn't support, that you want? Simon | -----Original Message----- | From: [email protected] [mailto:[email protected]] On | Behalf Of S. Alexander Jacobson | Sent: 28 February 2005 10:32 | To: Sander Evers; [email protected] | Subject: [Template-haskell] Re: [Haskell] Proposal: Allow "\=" for field update in record update syntax | | Since operators can't start with a ':', is there an in-principle | reason TH does not support : operators? The syntax below would be | really nice to have. | | | | On Fri, 18 Feb 2005, Sander Evers wrote: | | > | >> Then we could have e.g. (:=) and (:\=) and end up with a | >> syntax that looks like this: | >> | >> rec // field :\= fn . field2 := val | >> | >> And that is BETTER than the Haskell syntax that I originally proposed. | > | > This syntax is also nice for composition of update functions, which is useful | > with nested records: | > | > data Country = Country {capital :: City, ...} | > data City = City {inhabitants :: Int, ...} | > | > birth_in_capital :: Country -> Country | > birth_in_capital = capital :\= (inhabitants :\= (+1)) | > | > This also shows that it would be useful to make :\= associate to the right. | > | | ______________________________________________________________ | S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com | _______________________________________________ | template-haskell mailing list | [email protected] | http://www.haskell.org/mailman/listinfo/template-haskell