From @masak

<colomon> rakudo​: say (1..100).grep(10 < * < 20).gist
<p6eval> rakudo 9c6aed​: OUTPUT«1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85
86 87 88 89 90 91 9…
<colomon> b​: say (1..100).grep(10 < * < 20).perl
<p6eval> b 1b7dd1​: OUTPUT«(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64,
65, 66, 67, 68, 69, 70…
<colomon> niecza​: say (1..100).grep(10 < * < 20).perl
<p6eval> niecza v10-225-gbd53b44​: OUTPUT«(11, 12, 13, 14, 15, 16, 17,
18, 19).list␤»
<colomon> niecza++
<colomon> masak​: ^^ known bug?
<masak> colomon​: no, looks new to me.
* masak submits rakudobug
<masak> colomon++
<masak> nom​: say (1..100).grep(* < 20).perl
<p6eval> nom 9c6aed​: OUTPUT«(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19).list␤»
<masak> nom​: say (1..100).grep({ 10 < $_ < 20 }).perl
<p6eval> nom 9c6aed​: OUTPUT«(11, 12, 13, 14, 15, 16, 17, 18, 19).list␤»
<masak> innerestin'
<jnthn> masak​: Probably something to do with auto-currying

From @moritz

FWIW it's only the currying of the chained operator that fails, grep()
works fine.

Tested in t/spec/S02-types/whatever.t

The RT System itself - Status changed from 'new' to 'open'

From @timo

I made a branch "chained_whatevercode" for rakudo that annotates WhateverCode objects that were created for a "chain" op with the original arguments and when another WhateverCode with a chain op finds that WhateverCode instance in its arguments, it will flatten out the old arguments in itself.

After spectesting, I'll merge this into nom.

From @timo

fixed my branch, merged it into nom.

@timo - Status changed from 'open' to 'resolved'