Hi,
I found a missing symbol in documentation.
The missing symbol is `string->symbol`.
It contained in reference implementation but not in documentation.
https://github.com/scheme-requests-for-implementation/srfi-172/blob/d13a1174cb638155bbb008eb92d5fd3311e79622/srfi-172-functional.sld#L43

my pull request is here:
https://github.com/scheme-requests-for-implementation/srfi-172/pull/4

Regards,
Masaomi CHIBA