[Haskell-cafe] Linguistic hair-splitting
pumpkingod at gmail.com
Wed Jan 27 13:40:58 EST 2010
The list type constructor ( :: * -> *) is a functor, and if you add the
implementations of join/return (or just return and bind) those together make
the monad. The value-level list [3,5,8] is just a list :)
On Wed, Jan 27, 2010 at 1:30 PM, Andrew Coppin
<andrewcoppin at btinternet.com>wrote:
> Here's one for you to ponder.
> 7 is a number. 7 is an integer, and integers are numbers.
> 7 is not a field. 7 is an element of [at least one] field, but 7 itself is
> not a field.
> 7 is not a group. 7 is a member of the set of integers, but the set of
> integers is not a group either. The set of integers form a group when taken
> together with the addition operator. (And, actually, forms another,
> different, group when taken with the multiplication operator.)
> Now, here's the question: Is is correct to say that [3, 5, 8] is a monad?
> Is it correct to say that lists are a monad? Or would it be more correct to
> say that lists "form" a monad?
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