Non-H98 crusade, contd.

Malcolm Wallace Malcolm.Wallace at
Mon Feb 28 13:47:05 EST 2005

Andrew Pimlott <andrew at> writes:

> On Mon, Feb 28, 2005 at 01:45:25PM +0000, Malcolm Wallace wrote:
> > As examples of language features that should be removed or revised,
> > how about these:
> Perhaps
>     (d) the restriction of list comprehension to lists (instead of
>         MonadPlus)

You do realise that we used to have monad comprehensions in Haskell
1.4, and they were deliberately removed for Haskell'98?  The reason
was that error messages for beginners' code were rather baffling.
(And pretty baffling for some experts too!)  In any case, the
do notation is exactly analogous to list comprehensions with the
restriction to a single monad lifted.


More information about the Libraries mailing list