Documentation for infix (elem), infix ∈ assembled from the following types:

language documentation Sets, bags, and mixes

From Sets, bags, and mixes

(Sets, bags, and mixes) infix (elem), infix ∈

Returns True if $a is an element of $b, else False. More information, Wikipedia definition.

language documentation Operators

From Operators

(Operators) infix (elem), infix ∈

multi sub infix:<(elem)>($a,$b --> Bool:D)
multi sub infix:<∈>($a,$b --> Bool:D)

Membership operator.

Returns True if $a is an element of $b.

say 2 (elem) (1, 2, 3); # OUTPUT: «True␤» 
say 4 ∈ (1, 2, 3); # OUTPUT: «False␤» 

∈ is equivalent to (elem), at codepoint U+2208 (ELEMENT OF).