[Haskell-beginners] question on typeclasses and applicatives

Daniel Fischer daniel.is.fischer at web.de
Thu Sep 2 20:58:29 EDT 2010

On Friday 03 September 2010 02:11:22, Alec Benzer wrote:
> I guess I would then be concerned with why they didn't allow it in the
> standard (though I guess "well, it seemed to be a good idea at the
> time" answers that).

Well, you should ask why. For halfway sane languages like Haskell or C (C89 
or C99, not the mad pre-ANSI stuff), most things in the standard are there 
for good reasons. But some are there because it wasn't noticed early enough 
that it is in fact a bad idea. And of course lots of really good stuff 
isn't in the standard because at the time, nobody even thought of it (or 
had an idea how to implement it).
For completely insane languages like Perl or C++, one cannot assume good 
reasons of course.

> I think I also would want to avoid doing things not in the language
> standard on principle, since my instinct would tell me that if only a
> particular compiler implements, I shouldn't use it because it'll
> produce non-standard code. Though this sort of comes comes from C/C++
> where there are different compilers on different platforms, but I
> guess with haskell people pretty much use ghc everywhere?

Pretty much. For a long time, GHC has been the only usable implementation, 
so real world Haskell is de facto Glasgow Haskell. John Meacham's JHC is 
now close to being generally usable, I think. And UHC, the Utrecht Haskell 
Compiler, sounds like a promising project too.

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