chickadee » srfi-152 » string-concatenate-reverse

With no optional arguments, calling this procedure is equivalent to

(string-concatenate (reverse string-list))

If the optional argument final-string is specified, it is effectively consed onto the beginning of string-list before performing the list-reverse and string-concatenate operations.

If the optional argument end is given, only the characters up to but not including end in final-string are added to the result, thus producing

(string-concatenate
  (reverse (cons (substring final-string 0 end)
                 string-list)))

Example:

(string-concatenate-reverse '(" must be" "Hello, I") " going.XXXX" 7)
  ⇒ "Hello, I must be going."

Rationale: This procedure is useful when constructing procedures that accumulate character data into lists of string buffers, then convert the accumulated data into a single string when done. The optional end argument accommodates that use case by allowing the final buffer to be only partially full without having to copy it a second time, as string-take would require.

Note that reversing a string simply reverses the sequence of code points it contains. Caution should be taken if a grapheme cluster is divided between two string arguments.