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<div class="">More concretely, it's likely that Ord Bool is defined via `compare`, which is necessarily strict in both arguments.</div>
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Yes, this did come to mind. In general a non-strict `compare` would only make sense for `()`.
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<div class="">One of the relationships implied by the Ord typeclass is:<br class="">
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a <= b = True iff compare a b = EQ \/ compare a b = LT</div>
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<div class="">So wouldn’t it make sense to define `compare` in terms of the “weaker” relations? It seems very unhaskelly to do the unnecessary work of evaluating the second argument to a relation when we already know what the result should be.</div>
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<div class="">Vilem</div>
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<div class="">On 2 Jan 2019, at 10:29, Isaac Elliott <<a href="mailto:isaace71295@gmail.com" class="">isaace71295@gmail.com</a>> wrote:</div>
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<div class="">One of the relationships implied by the Ord typeclass is:<br class="">
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a <= b = True iff compare a b = EQ \/ compare a b = LT</div>
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<div class="">If we write an alternative definition of (<=) that is only strict in its first argument:<br class="">
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False <= _ = True</div>
<div class="">True <= x = x</div>
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<div class="">Then it's impossible to write `compare` in a way that's consistent with that relation.</div>
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<div class="">More concretely, it's likely that Ord Bool is defined via `compare`, which is necessarily strict in both arguments.</div>
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<div dir="ltr" class="">On Wed, 2 Jan. 2019, 7:47 pm V.Liepelt, <<a href="mailto:V.Liepelt@kent.ac.uk" target="_blank" class="">V.Liepelt@kent.ac.uk</a>> wrote:<br class="">
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I am surprised to find that `False <= undefined = undefined`.<br class="">
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What justifies (<=) to be strict in both arguments?<br class="">
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Vilem<br class="">
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