Formal comment #182 (enhancement)

Port predicates (New predicates wanted for different subtypes of ports)
Reported by: 	John Cowan
Version:	5.92

Currently R5.92RS has input-port? and output-port? and binary-port? I
propose adding textual-port?, input/output-port?, file-port?,
string-port?, and bytevector-port? with the obvious semantics.

A textual-port? predicate would be technically redundant, as by the
letter of R5.92RS all non-binary ports are textual; however, a
particular implementation might add ports which were neither binary
nor (in the general sense) textual, with new input or output
operations.


RESPONSE:

The textual-port? predicate will be added to the next draft.

File, string, and bytevector ports have no standard operations
that would require them to be distinguishable, so the editors
did not perceive a need for the file-port?, string-port?, and
bytevector-port? predicates.

Since the input/output-port? predicate would compute the
obvious conjunction, the editors did not perceive a need for
it either.