I think the process is exactly the same as the ruby example, except for the fact that while in ruby it was a hack, in racket, a programming-language programming

I think the process is exactly the same as the ruby example, except for the fact that while in ruby it was a hack, in racket, a programming-language programming language, is explicitly designed to allow for this kind of process. The linked website just mentions that the algol60 package also provides additional functions that allow executing over strings. The default mode of usage is to place a "#lang algol60" at the start of your files, and that configures the lexer/parser to allow the rest of the file to be parsed and interpreted as ALGOL code (just check out the examples in the packages's git forge page).