fmtis
A library of procedures for formatting Scheme objects to text in various ways, and for easily concatenating, composing and extending these formatters efficiently without resorting to capturing and manipulating intermediate strings.
This release also addresses a long-time pet peeve of mine – you can now format exact non-integral rationals to arbitrary precision. Rationals provide extended precision, but until now it was always difficult to see that precision in a human-readable manner.
(via ikarus)