The ~N format specifier in SRFI-19's date->string is documented to show the nanoseconds value, with zero padding. The documentation explicates further by showing as an example a string of nine zeroes. In fact the implementation only pads to seven digits, and so produces incorrect output for and nanoseconds value in the range [0, 100000000):
scheme@(guile-user)> (use-modules (srfi srfi-19)) scheme@(guile-user)> (date->string (make-date 0 5 34 12 26 3 2017 0) "~N") $1 = "0000000" scheme@(guile-user)> (date->string (make-date 2 5 34 12 26 3 2017 0) "~N") $2 = "0000002" scheme@(guile-user)> (date->string (make-date 200 5 34 12 26 3 2017 0) "~N") $3 = "0000200" scheme@(guile-user)> (date->string (make-date 200000 5 34 12 26 3 2017 0) "~N") $4 = "0200000" scheme@(guile-user)> (date->string (make-date 99999999 5 34 12 26 3 2017 0) "~N") $5 = "99999999" scheme@(guile-user)> (date->string (make-date 200000000 5 34 12 26 3 2017 0) "~N") $6 = "200000000" The padding clearly has to be to the full nine digits. -zefram
