collapse ( ... seq quot: ( ... elt -- ... ? ) elt -- ... seq' )

Vocabulary

sequences.extras

Inputs

seq	a sequence
quot	a quotation with stack effect ( ... elt -- ... ? )
elt	an object

Outputs

seq'	a sequence

Word description

Generate a new sequence where all runs of elements for which the predicate returns true are replaced by a single instance of elt.

See also

compact

Examples

Collapse multiple spaces in a string down to a single space

USING: kernel prettyprint sequences.extras ; " Hello, crazy world " [ CHAR: \s = ] " " collapse .
" Hello, crazy world "

Definition

USING: kernel sequences splitting ;

IN: sequences.extras

: collapse
    ( ... seq quot: ( ... elt -- ... ? ) elt -- ... seq' )
    [ split-when ] dip
    [ [ harvest ] dip join ]
    [ [ first empty? ] dip [ prepend ] curry when ]
    [ [ last empty? ] dip [ append ] curry when ] 2tri ; inline