: count-a-word-chars ( List -- Int )
    [ 0 string.char-at 97 i.= ] list.filter
    0 [ string.length i.+ ] list.fold
;

: test-combine ( -- )
    "apple banana apricot cherry" " " string.split count-a-word-chars
    12 test.assert-eq   # "apple" (5) + "apricot" (7) = 12
;
