streamp

(streamp object)

Returns t if object is a stream and nil otherwise. A stream is a self-describing VALUE -- open, make-string-input-stream, make-string-output-stream and the socket constructors all answer one -- so an integer is NOT a stream, and a library that dispatches on "a file descriptor versus a Lisp stream" ((etypecase s (integer ...) (stream ...))) routes a rontolisp stream correctly. The standard-output designator t (what *standard-output* is bound to) counts as a stream too, and so do a Gray stream instance -- any instance of a class descending from rontolisp:fundamental-stream -- and a synonym stream. The stream type specifier used by check-type/typecase is backed by the same test.

Its subtype names are exact, because the value carries the kind it was built with: file-stream is true of a stream open answered, string-stream of one the two string-stream constructors answered, and synonym-stream of a make-synonym-stream value. readtable is the type of the opaque nil token *readtable* holds. A stream PRINTS as #<STREAM> -- one text on every backend, with no backend-local handle or identity hash in it. Available on all backends except --no-gc.