You're misreading the question. It's asking you to show that the category
induced by the <= relation fails associativity if you add an extra
morphism.
On Mar 29, 2014 1:19 AM, "John M. Dlugosz"
on https://en.wikibooks.org/w/index.php?title=Haskell/ Category_theory&stable=0#Hask.2C_the_Haskell_category
the second exercise in the box (see illustration there) asks "(Harder.) If we add another morphism to the above example, it fails to be a category. Why? Hint: think about associativity of the composition operation."
There are no answers-to-exercises. Can someone explain to me why adding another function with the same type causes the Haskell type system to no longer form the Hask category?
(scratching head)
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