%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/test.end {
    ( ) print
    test.count 0 gt {
        (Passed ) print
        test.pass (...) cvs print
        (/) print
        test.count (...) cvs print
        ( \() print
        test.pass 100 mul test.count idiv (...) cvs print
        (%\)) print
        (\r\n) print
    } if
} bind def

/reduce { % array proc -> value
    2 dict begin
    /p exch def
    /a exch def
    a 0 get
    1 1 a length 1 sub {
        a exch get
        p
    } for
    end
} bind def

/test {
    /test.count test.count 1 add def
    {
        /test.pass test.pass 1 add def
    } {
        ( ) print
        test.count (....) cvs print
        (-fail) print
    } ifelse
} bind def

/listmax {
    { max } reduce
} bind def

/test.start {
    print (:) print
    /test.pass 0 def
    /test.count 0 def
} bind def

/listmin {
    { min } reduce
} bind def


% end included library code

/monotonicarray {
    1 dict begin
    /l exch def
    [
        0 1 l length 2 sub {
            dup 1 add l exch get exch l exch get sub
        } for
    ] dup listmin exch listmax mul 0 ge
    end
} bind def

(monotonicarray) test.start
[1 2 2 3] monotonicarray test
[1 3 2] monotonicarray not test
[6 5 5 4] monotonicarray test
test.end