apfl/examples/mandelbrot.apfl

width := 80
height := 24
maxiter := 100

V+ := { a1::b1 a2::b2 ->
    (+ a1 a2)::(+ b1 b2)
}

V* := { a1::b1 a2::b2 ->
    (- (* a1 a2) (* b1 b2))::(+ (* a1 b2) (* b1 a2))
}

Vsquared := { x -> V* x x }

Vsquared-abs := { a::b ->
    + (* a a) (* b b)
}

mandel := {
0 _ _ -> true
_ _ _?(has Vsquared-abs > 4) -> false
n c z -> mandel (-- n) c (V+ (Vsquared z) c)
}

mindim := if (< width height) {width} {height}
scale := / 2 mindim
iterdim := { dim body ->
    half := / dim 2
    for (- half) half { x ->
        body (* scale x)
    }
}

iterdim height { b ->
    line := ""
    iterdim width { a ->
        line = & line (if (mandel maxiter a::b 0::0) {"#"} {" "})
    }
    gc 'collect
    print line
}