(string-alter! string1 integer1 integer2 string2) -> null
Using the Indexing System: a portion of String1, from index indicated by Integer1 for a length indicated by Integer2, is replaced with String2.
>> (define a "a cdefgh") :: "a cdefgh" >> (string-alter! a 1 1 "b") :: null >> a :: "abcdefgh" >> (string-alter! a 1 5 "BCD") :: null >> a :: "aBCDgh"