More complicated code, but no intermediate arrays

inspector.factor

: first-column-width ( table model -- width )
    [
        [ font>> dup ] keep
        renderer>> column-titles first cell-dim nip +
    ] dip
    value>> dup sequence? [
        length 1 - unparse-short swapd cell-dim nip + max
    ] [
        make-mirror [
            ! font prev key value
            drop unparse-short [ over ] dip cell-dim nip + max
        ] assoc-each nip
    ] if ;

: <inspector-table> ( model -- table )
    [
        [ make-slot-descriptions ] <arrow> inspector-renderer <table>
            [ invoke-primary-operation ] >>action
            line-color >>column-line-color
            6 >>gap
            15 >>min-rows
            15 >>max-rows
            40 >>min-cols
            40 >>max-cols
            monospace-font >>font
            dup
    ] keep first-column-width 0 2array >>fixed-column-widths ;