[Haskell-cafe] Monad laws

Alexander Solla alex.solla at gmail.com
Sun Jun 29 23:05:29 UTC 2014

> Is x == x being false really any more surprising than x + 1  == x being
> true?

Yes, a lot more.  Equality is a symmetric relation.  So "x equals x" is
true for every x.  A logic/language in which that is not true is unsound.

x + 1 == x is just an equation.  Coming up with a theory where it holds is
straightforward.  For example, addition followed by the "fractional part"
operation, on the set [0,1].
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