; Jonathan Frech, 2021-12-22
; see: https://blog.jfrech.com/248/
; compilation one-liner (zsh):
;     % sh =(curl -fsSL blog.jfrech.com/248/run.sh) "$(realpath tree.ma)"

; compiled brainfuck:
;     >[-]+++++>[-]>[-]<<[->+>+<<]>>[-<<+>>]<[->[-]>[-]<<<[->>+>+<<<]>>>[-<<<+>>
;     >][-]>[-]<<<[->>+>+<<<]>>>[-<<<+>>>]<[-<->][-]>[-]<<[->+>+<<]>>[-<<+>>]<<[
;     ->+<]>->[-]>[-]<<<<[->>>+>+<<<<]>>>>[-<<<<+>>>>][-]>[-]<<<[->>+>+<<<]>>>[-
;     <<<+>>>]<<[>>[-]++++++++++++++++++++++++++++++++.<<-]>[>[-]+++++++++++++++
;     +++++++++++++++++++++++++++.<-]>[-]++++++++++.<<<<<]<+>[-]<[-->+<]>>[-]>[-
;     ]<<[->+>+<<]>>[-<<+>>][-]>[-]<<<[->>+>+<<<]>>>[-<<<+>>>]<<[>>[-]++++++++++
;     ++++++++++++++++++++++.<<-]>[>[-]+++++++++++++++++++++++++++++++++++++++++
;     +.<-]>[-]++++++++++.

(macro line:zz (w s) (
    (while:re w (
        (putc:v ' ')
        (dec:a w)))
    (while:re s (
        (putc:v '*')
        (dec:a s)))
    (putc:v '\n')))
(derive line:zz line:rr)

(derive divmod:arw divmod:avw)

; `height` ought to be odd
(macro main:v (height) (
    (let:nve $height height (
        (let:nre $w $height (
            (while:re $w (
                (dec:a $w)
                (let:nre $height-w $height (
                    (sub:ra $w $height-w)
                    (let:nre $s $height-w (
                        (add:za $height-w $s)
                        (dec:a $s)
                        (line:rr $w $s)))))))))

        ; `$height` is odd
        (inc:a $height)
        (let:nve $height/2 0 (
            (while:re $height (
                (dec:a $height)
                (dec:a $height)
                (inc:a $height/2)))
            (line:rr $height/2 $height/2)))))))

(main:v 5)