On Monday, 14 March 2016 at 08:04:18 UTC, deadalnix wrote:
Right now, I'm repeating the following pattern many times :
range.map!(x => cast(Foo) x).filter!(x => x !is null)
This reminds me of a function in OCaml extended stdlib that I've
used quite often and really miss in D:
filter_map : ('a -> 'b option) -> 'a list -> 'b list
"filter_map f l call (f a0) (f a1).... (f an) where a0..an are
the elements of l. It returns the list of elements bi such as f
ai = Some bi (when f returns None, the corresponding element of l
is discarded)."
Or its variant for OCaml's analog of ranges:
filter_map : ('a -> 'b option) -> 'a t -> 'b t
"filter_map f e returns an enumeration over all elements x such
as f y returns Some x, where y is an element of e."
It is really convenient and comes handy in many situations.
However it requires some common Option/Maybe type that different
libraries could use.
