rnrs mutable-strings

The (rnrs mutable-strings (6)) library provides the string-set! and string-fill! procedures, which allow the content of strings to be modified “in-place.”

These procedures are identical to the ones provided by Guile’s core library. See String Modification, for documentation. All strings in Guile are mutable; consequently, these procedures will never throw the &assertion condition described in the R6RS libraries specification.