occurrence-count-by ( seq quot: ( elt -- elt' ) -- hash seq' )


Vocabulary
sequences.extras

Inputs
seqan object
quota quotation with stack effect ( elt -- elt' )


Outputs
hashan object
seq'an object


Definition
USING: kernel ;

IN: sequences.extras

: occurrence-count-by
( seq quot: ( elt -- elt' ) -- hash seq' )
[ [ nip ] ] dip [ over inc-at* drop ] compose compose
[ H{ } clone ] 2dip { } 0accumulate-as ; inline