Details
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Type:
Defect
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Status:
Open
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Priority:
Major
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Resolution: Unresolved
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Affects Version/s: None
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Fix Version/s: None
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Component/s: None
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Labels:None
Description
One of the monad laws is that (m-bind (m-result v) f) should be the same as (f v). However, this is not the case in maybe-m:
user=> (with-monad maybe-m (m-bind (m-result nil) nil?))
nil
user=> (nil? nil)
true
The crux of the problem is that in algo.monad's maybe-m, there is no way to wrap a nil in a Just-like container.
Just realized that that demonstration doesn't actually work, because the function passed to m-bind is supposed to return a monadic value. Here's a better one:
user=> (with-monad maybe-m (m-bind (m-result nil) (comp m-result nil?)))
nil
user=> (with-monad maybe-m ((comp m-result nil?) nil))
true