Small correction, I believe "contramap" is logically wrong.
Just because we have a function from B->A doesn't necessarily means that applying these functions and then using equal is the same as applying equal to the instances of B.
it lacks assumptions for this to be true.
for example:
lets say B is simply numbers, and A are simply strings,
the function that converts these operate by the following logic, all positive numbers transformed to the latter 'p', and all the negatives to the latter 'n',
so,
f(2) === f(3)
but 2!==3.
Great article,
Small correction, I believe "contramap" is logically wrong.
Just because we have a function from B->A doesn't necessarily means that applying these functions and then using equal is the same as applying equal to the instances of B.
it lacks assumptions for this to be true.
for example:
lets say B is simply numbers, and A are simply strings,
the function that converts these operate by the following logic, all positive numbers transformed to the latter 'p', and all the negatives to the latter 'n',
so,
f(2) === f(3)
but 2!==3.
Actually they are equal, under the equivalence relation induced by the function
fwhich is defined as:see "Equivalence kernel" here en.wikipedia.org/wiki/Equivalence_...