Class or parameterized type?

[Graham Klyne]

At 11:41 20/03/2003 -0800, you wrote:
> > I suppose this is the multi-parameter type class extension you
> > mentioned.  Can you say where this extension is described, and how widely
> > implemented it is?
>
>GHC (with the flag -fglasgow-exts) and Hugs (with the flag -98)
>implement it. I think NHC does too.

Excellent!

Your (previous) code example turned out to be extremely helpful.  I was 
having a hard time figuring out what I needed to do to get my code to work 
in a reasonable fashion for my purposes, and it provided just the pointers 
I needed to break the logjam.  Having it in a complete form with simple 
test cases was particularly helpful, and having got the type signatures 
sorted out I'm making much better progress on my project.  Much appreciated.

Having tried briefly to work without them, I now think multi-parameter 
classes are a really important extension for a range of programming 
tasks.  Having support in Hugs and GHC seems to me like an important 
threshold of support.

Thank you for your help.

#g


-------------------
Graham Klyne
<GK@NineByNine.org>
PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E