[Haskell-cafe] Alternative name for return

Joe Quinn headprogrammingczar at gmail.com
Wed Aug 7 22:38:23 CEST 2013


On 8/7/2013 11:00 AM, David Thomas wrote:
> twice :: IO () -> IO ()
> twice x = x >> x
>
> I would call that evaluating x twice (incidentally creating two 
> separate evaluations of one pure action description), but I'd like to 
> better see your perspective here.

x is only evaluated once, but /executed/ twice. For IO, that means 
magic. For other types, it means different things. For Identity, twice = id!
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