[Haskell-cafe] Could someone teach me why we use Data.Monoid?

Stephen Tetley stephen.tetley at gmail.com
Fri Nov 13 12:13:30 EST 2009

2009/11/13 Magnus Therning <magnus at therning.org>:
> On Fri, Nov 13, 2009 at 4:52 PM, Andrew Coppin
> <andrewcoppin at btinternet.com> wrote:

>> This is the thing. If we had a class specifically for containers, that could
>> be useful. If we had a class specifically for algebras, that could be
>> useful. But a class that represents "any possible thing that can technically
>> be considered a monoid" seems so absurdly general as to be almost useless.
>> If you don't know what an operator *does*, being able to abstract over it
>> isn't especially helpful...
>> ...in my humble opinion. (Which, obviously, nobody else will agree with.)
> But can't you say exactly the same about Monads?

There's a comment about monads for programming that goes along the lines of

'Monads are a just a structure (ADT?), but they happen to be a very good one."

Does anyone know the original version (not my paraphrase) and who the
originator was?



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