streamp

(streamp object)

Returns t if object is a stream and nil otherwise. Streams are opaque integer handles across all backends, so this is a lite test equivalent to integerp; the standard-output designator t (what *standard-output* is bound to) also counts as a stream. The stream type specifier used by check-type/typecase is backed by the same test. Its subtype names resolve too: synonym-stream has an exact test (a synonym stream is the one stream kind that is a value rather than a handle), while file-stream is lite in the same direction streamp is -- it is true of every handle stream, because nothing in a handle tells a file's from a string stream's. readtable is the type of the opaque nil token *readtable* holds. Available on all backends except --no-gc.