text: 'Given$a$text$file$of$many$lines,$where$fields$within$a$line$
are$delineated$by$a$single$\'dollar\'$character,$write$a$program
that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$
column$are$separated$by$at$least$one$space.
Further,$allow$for$each$word$in$a$column$to$be$either$left$
justified,$right$justified,$or$center$justified$within$its$column.'

align: action text; position;

    # split text into 2D array of lines and words
    lines : { for text.split ~\$?\r?\n~ { for a.split '$' a end } end }

    # calculate max required width for each column
    widths: { for lines for a here[b]: a.length.max here[b]? ends }

    spaces: action out ("%%%ds" in).format '' end

    # formatting functions
    left: action word; width;
        pad: width-word.length
        print "%s%s " word spaces pad
    end
    right: action word; width;
        pad: width-word.length
        print "%s%s " spaces pad word
    end
    center: action word; width;
        pad: (width-word.length)/2
        print "%s%s%s " spaces pad.floor word spaces pad.ceil
    end

    if position.match ~^(left|center|right)$~ for lines
        for a local[position] a widths[b] end say ''
    ends say ''
end

align text 'left'
align text 'center'
align text 'right'