[Haskell-cafe] monads with take-out options

Jason Dagit dagit at codersbase.com
Mon Nov 24 17:27:26 EST 2008

2008/11/24 Greg Meredith <lgreg.meredith at biosimilarity.com>

> Haskellians,
> Some monads come with take-out options, e.g.
>    - List
>    - Set
> In the sense that if unit : A -> List A is given by unit a = [a], then
> taking the head of a list can be used to retrieve values from inside the
> monad.
> Some monads do not come with take-out options, IO being a notorious
> example.

I think the take-out option for IO is usually called 'main'. :)

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