patch applied (haskell-prime-status): add ""Make $ left associative, like application"

Don Stewart dons at
Wed Apr 23 17:39:13 EDT 2008

> Hi
> >  I think it is reasonable to look closely at the motivations for
> >  wanting to retain the $ as is. Looking through this thread, I can find
> >  only a single complaint raised (albeit an important one), namely
> >  backwards compatibility. Yes, such a change would likely break quite a
> >  few my modules. But like Cale, I would never have expected H' to be
> >  fully backwards compatible with H98, and thus there would have to be
> >  some way to migrate anyway. This one seems pretty simple, just let the
> >  old Prelude be Haskell98.Prelude and import that in old code. Of
> >  course changes that break backwards compatibility should not be made
> >  frivolously, but I find it hard to buy having only that as an argument
> >  for a change that otherwise seems highly reasonable.
> I don't want to have to do a brain mode-change between "in a
> Haskell98.Prelude" module and "in a Prelude" module. I don't want to
> copy code between modules and have it do different things.
> We also should remember that a large number of academic papers are
> written in Haskell, and unlike libraries, don't get "update releases"
> made. This is not a minor tweak - it will break a massive number of
> programs.
> >  ps. Though to be honest I really don't see why we don't simply add
> >  another operator instead of changing an existing one... :-)
> (£) anyone?* This seems a massively more sensible idea.

I'm very suspicious about the power/weight ratio of this change.
Normally, for simple value-level stuff like this, provide both options:

    mapM / forM. =<< >>=

So how about, rather than break things, just provide an alternative to ($).

-- Don

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