G'day all.
Quoting Steve Downey <[EMAIL PROTECTED]>:
> from what you just told me, it's not an artifact of the pf style, but
> that maximally reusable functions will be expressible in a pointsfree
> style.
Not necessarily. (There's a fairly obvious reductio ad absurdum argument
as to why: at least the primitives like "map" and "foldr" need to be
expressed in a pointed way!)
Pointsfree functions are not necessarily maximally reusable, but they're
usually maximally refactorable.
As an example, the associative law for monads looks like this in
pointed style:
(m >>= k1) >>= k2 = m >>= (\x -> k1 x >>= k2)
Applying this law from left to right requires introducing a fresh
variable, which involves checking for name clashes, even if only
briefly, and introduces a new name that doesn't necessarily have a
good "meaning".
Applying the law from right to left might require a lot of fiddling
with k1 to get it in the right form, and checking that the variable,
x, is not free in m or k2.
In point-free style, the associative law for monads looks like this:
join . join = join . fmap join
In either direction, this is almost trivial.
Cheers,
Andrew Bromage
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