On Thu, Jul 27, 2006 at 02:57:20PM +0200, Doaitse Swierstra wrote:
On Jul 27, 2006, at 1:35 PM, Niklas Broberg wrote:
I would really like to see this implemented, and I don't think the above is serious enough that we shouldn't. There may be some that don't agree though. Speak up now, or forever hold your peace!
Me too, this sounds really cool!
We alreday are at a stage where first year students trying to master haskell get error messages like
"Bool is not an instance of the class Num"
if they accidently write 1 + True (or something equivalent, but less obvious).
I think this is not a language issue so much as a compiler issue, and I don't think it's a sound idea to limit the language or libraries based on the existing poor error messages. If the above gave a message like (+) requires an argument of class Num, but "True" is of type Bool, which is not in class Num. I don't think there would be a problem. In general, I think classes should be used more, rather than less, and if that means we need a SoC project to improve the clarity of error messages, then that's what needs to be done. (I'll admit, I'm unlikely to do this...)
If you want to mess around why not call the function "provided" or something similar.
Or perhaps (?:) or something like that, which could be used infix to evoke the idea of C's e1 ? e2 : e3 syntax. "provided" to me is less clear than "cond" since it has other meanings, and isn't borrowed from any language that I'm familiar with, like "cond" is. -- David Roundy