Commit afaf1a16 authored by Jan Moringen's avatar Jan Moringen
Browse files

use implementation's EMPTYP when available

Using the implementation's EMPTYP has the potential advantage of
supporting user-defined sequence types (as is the case with SBCL).

This commit tests for SEQUENCE:EMPTYP and defines ALEXANDRIA:EMPTYP in
terms of it.

For implementations that do not provide SEQUENCE:EMPTYP, nothing
parent 8b89a71b
......@@ -155,6 +155,12 @@ that are not lists."
`(or proper-list
(and (not list) sequence)))
(eval-when (:compile-toplevel :load-toplevel :execute)
(when (and (find-package '#:sequence)
(find-symbol (string '#:emptyp) '#:sequence))
(pushnew 'sequence-emptyp *features*)))
(defun emptyp (sequence)
"Returns true if SEQUENCE is an empty sequence. Signals an error if SEQUENCE
is not a sequence."
......@@ -162,6 +168,14 @@ is not a sequence."
(list (null sequence))
(sequence (zerop (length sequence)))))
(declaim (ftype (function (sequence) (values boolean &optional)) emptyp))
(setf (symbol-function 'emptyp) (symbol-function 'sequence:emptyp))
(define-compiler-macro emptyp (sequence)
`(sequence:emptyp ,sequence))
(defun length= (&rest sequences)
"Takes any number of sequences or integers in any order. Returns true iff
the length of all the sequences and the integers are equal. Hint: there's a
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