?change-at ( ..a key assoc quot: ( ..a value -- ..b newvalue ) -- ..b )

Vocabulary

assocs

Inputs

key	an object
assoc	an assoc
quot	a quotation with stack effect ( ..a value -- ..b newvalue )

Outputs

None

Word description

If the key exists in the assoc, applies the quotation to the value associated with key, storing the new value back in the assoc.

Side effects

Modifies assoc

See also

change-at, change-nth, change

Definition

USING: kernel ;

IN: assocs

: ?change-at
    ( ..a key assoc quot: ( ..a value -- ..b newvalue ) -- ..b )
    2over [ set-at ] 2curry compose [ at* ] dip [ drop ] if ;
    inline