Proposal: Add &&& and *** to Data.Tuple

ajb at ajb at
Thu Sep 20 22:46:28 EDT 2007

G'day all.

Quoting Stefan O'Rear <stefanor at>:

> The reason ++ and mplus is so similar is that they used to be the same;
> (++) *was* the MonadPlus class member.  Cale Gibbard explains this as
> {{{Quite a few people on the Haskell 98 committee had an irrational fear
> of polymorphism.}}}

That's a slight exaggeration.  They actually had nightmares involving
trying to explain to their undergraduate students what the inevitable
type error messages meant.

At a time when Haskell was mostly a teaching/research language, this made
a certain amount of sense.  Now that Haskell is officially Cool(tm), the
argument is much weaker.

Andrew Bromage

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