https://issues.dlang.org/show_bug.cgi?id=13595
Issue ID: 13595 Summary: A possible problem with std.algorithm.groupBy Product: D Version: D2 Hardware: x86 OS: Windows Status: NEW Severity: normal Priority: P1 Component: Phobos Assignee: nob...@puremagic.com Reporter: bearophile_h...@eml.cc Perhaps I have not fully understood the usage of std.algorithm.groupBy. This is Haskell: Prelude> import Data.List Prelude Data.List> groupBy (\x y -> (mod (x*y) 3) == 0) [1,2,3,4,5,6,7,8,9] [[1],[2,3],[4],[5,6],[7],[8,9]] D code: void main() { import std.stdio, std.algorithm, std.array, std.range; [1,2,3,4,5,6,7,8,9] .groupBy!((x, y) => ((x * y) % 3) == 0) .take(20) .writeln; } Output of the D code: [[], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], []] Please close down this issue if this behavour is expected and correct. --