futures.nim

from future import `=>`

var arr = [1,2,3,4]
arr.map (i => echo(i))
#futures.nim(4, 3) Error: type mismatch: got (Array constructor[0..3, int])
#but expected one of:
#system.map(data: var openarray[T], op: proc (var T){.closure.})
#system.map(data: openarray[T], op: proc (T): S{.closure.}): seq[S]