Hi,
Below is my attempt to code the first example from Walder’s Theorems for
free! paper.
I am not sure about what is being proved.
Using the notation from the paper does the proof establish a property of map, r, composition or the relationship between all three?
{-# LANGUAGE ExistentialQuantification #-}
import Data.Char
r :: forall a . [a] -> [a]
r = reverse
g :: Char -> Int
g = ord
(map g . r $ ['a','b','c']) == (r . map g $ ['a','b','c'])
Regards,
Pat
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