make-string - construct a string
(import (rnrs)) ;R6RS
(import (rnrs base)) ;R6RS
(import (scheme r5rs)) ;R7RS
(import (scheme base)) ;R7RS
(make-string k)
(make-string k char)
Returns a newly allocated string of length k. If char is given,
then all elements of the string are initialized to char, otherwise the
contents of the string are unspecified.
(make-string 3 #\a) => "aaa"
This procedure can be a code smell because it is commonly used when programs
construct strings using mutation. If characters are generated in sequential
order then an alternative is to use open-string-output-port(3scm) or
call-with-string-output-port(3scm). This additionally has the benefit
that the length of the output does not need to be known ahead of time.
This procedure is provided for programs that need to efficiently construct
strings that are mutated in random order.
Implementations are allowed to have a unique zero-length string.
This procedure can raise exceptions with the following condition types:
- &assertion (R6RS)
- The wrong number of arguments was passed or an argument was outside its
domain.
- R7RS
- The assertions described above are errors. Implementations may signal an
error, extend the procedure's domain of definition to include such
arguments, or fail catastrophically.
- Unsupported characters (R7RS)
- It is an error to pass this procedure a character which the implementation
does not support. 7-bit ASCII (except #\null) must be supported.
Any other character is optional and potentially an error (as described
above). You can use the full-unicode feature identifier in
cond-expand(3scm) to check if all of Unicode 6.0 is supported.
R2RS, R3RS, R4RS, IEEE Scheme, R5RS, R6RS, R7RS
This procedure appears in all Scheme reports since R2RS. Scheme before then
(running on MACLISP) also had strings, but there does not appear to have been
a constructor.
Implementations vary in how well they handle a large k.