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| PROGRAMMING WITH EFFECTS | |
| Graham Hutton, January 2015 | |
| Shall we be pure or impure? | |
| The functional programming community divides into two camps: | |
| o "Pure" languages, such as Haskell, are based directly | |
| upon the mathematical notion of a function as a | |
| mapping from arguments to results. |
| {-# LANGUAGE TypeFamilies #-} | |
| import Data.Function (on) | |
| import Control.Applicative | |
| data EventData e = EventData { | |
| eventId :: Int, | |
| body :: Event e | |
| } |