To print the Unicode character U+2665, i.e. , to the terminal, you must express it in UTF8:
- Unicode code point: U+2665
- UTF8 : \xe2\x99\xa5
Scheme] (display "\xe2\x99\xa5")
If you want to print it in an equation within a document, you must use the code point
or copying the character directly:
Scheme] (stree->tree `(equation* (document (sqrt "AAA♥BBB<#2665>CCC"))))
From your init file, both of these forms will work:
(display "\xe2\x99\xa5\n")
(display "♥\n")