Or overloading the `whitespace operator' for several kinds of application. On May 28, 2009, at 9:50 AM, Augustsson, Lennart wrote:

And explicit desugaring of list syntax.

-----Original Message----- From: Sittampalam, Ganesh [mailto:ganesh.sittampalam@credit- suisse.com] Sent: 28 May 2009 08:46 To: Simon Peyton-Jones; Sebastiaan Visser; Haskell Cafe Cc: Augustsson, Lennart Subject: RE: [Haskell-cafe] Bool as type class to serve EDSLs.

There are multiple possible classes that you might want under different circumstances (I think the most interesting issue is whether the class (==), (>) etc is in has a fundep from the type of the thing being compared to the type of the boolean), but if NoImplicitPrelude (or some other extension) just desugars if-then-else into ifthenelse (with a default implementation of ifthenelse somewhere) I think that would be enough.

Of course once you've got ifthenelse you find yourself wanting explicit desugaring of pattern matching (could view patterns help here?), recursion (into an explicit use of fix), etc...

Cheers,

Ganesh

Simon Peyton-Jones wrote:

...

You are absolutely right about the tantalising opportunity. ...