> 2) If a Scheme system supports reader macros (e.g. Racket), the `read'
> procedure should be considered unsafe; thus, it may be best to remove
> it from (srfi 172) and (srfi 172 functional).

Would it be possible to mandate that the SRFI 172 environment provide a
version of `read` using standard syntax with no extensions?

What about custom writers for user-defined data types? Common Lisp lets
users specialize the `print-object` method for their own types; some
Scheme probably has something similar, or will eventually.

Is `read` useful in the environment? `write` probably is, but could we
make do with just `write-char`, `write-string`, `write-u8` and
`write-bytevector`? There's `number->string` and `symbol->string` for
the most frequently needed conversions.