This is an attempt to determine which Schemes treat literal strings as immutable, using the code
(define y "abcde") (string-set! y 0 #\c) yMutates y to the value "cbcde": MIT, Gambit, Chicken, Bigloo, Detroit, Stalin, Scheme->C, SCM, Chez, Vicare, Larceny, Ypsilon, JScheme, RScheme, S7, Unlikely, BDC, XLisp, UMB, Elk, SXM, Inlab, Foment, Picrin, Chibi
Raises an error about mutating an immutable object: Racket, Gauche, Scheme48/scsh, Guile, Kawa, SISC, Mosh, IronScheme, STklos, KSi, SigScheme, TinyScheme, Scheme 9, Sizzle, Sagittarius
Does not support string-set!: NexJ, Shoe, Rep, Llava, FemtoLisp, Dfsch, Owl Lisp (no mutation)
Does not support #\c: MiniScheme, SIOD, Schemik