Hi Trevor,
In Scheme, the = function is for comparing numbers, and nothing else. For colors, you want equal? .
~ $ guile2.2
GNU Guile 2.2.7
Copyright (C) 1995-2019 Free Software Foundation, Inc.
Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.
Enter `,help' for help.
scheme@(guile-user)> (= 1 2)
$1 = #f
scheme@(guile-user)> (= 1 1)
$2 = #t
scheme@(guile-user)> (= 1 1.0)
$3 = #t
scheme@(guile-user)> (= 'a 'b)
<unnamed port>:4:0: In procedure =: Wrong type argument in position 1: a
Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [1]> ,q
scheme@(guile-user)> (equal? 1 2)
$4 = #f
scheme@(guile-user)> (equal? 1 1)
$5 = #t
scheme@(guile-user)> (equal? 1 1.0)
$6 = #f
scheme@(guile-user)> (equal? 'a 'b)
$7 = #f
Thank you so much; exactly what I needed to know.