ppx_compose - Inlined Function Composition
ppx_compose is a simple syntax extension which rewrites code containing
function compositions into composition-free code, effectively inlining the
composition operators. The following two operators are supported
let (%) g f x = g (f x) let (%>) f g x = g (f x)
Corresponding definitions are not provided, so partial applications of
(%>) will be undefined unless you provide the definitions.
The following rewrites are done:
A composition occurring to the left of an application is reduced by
applying each term of the composition from right to left to the
argument, ignoring associative variations.
A composition which is not the left side of an application is first
turned into one by η-expansion, then the above rule applies.
Any partially applied composition operators are passed though unchanged.
h % g % f ==> (fun x -> h (f (g x))) h % (g % f) ==> (fun x -> h (f (g x))) (g % f) (h % h) ==> g (f (fun x -> h (h x)))
Is It Needed?
Recent flambda-enabled compilers can inline the following alternative
definitions of the composition operators :
let (%) g f = (); fun x -> g (f x) let (%>) f g = (); fun x -> g (f x)
so this syntax extension will likely be retired at some point.