File: features.lisp

package info (click to toggle)
acl2 8.0dfsg-1
  • links: PTS
  • area: main
  • in suites: buster
  • size: 226,956 kB
  • sloc: lisp: 2,678,900; ansic: 6,101; perl: 5,816; xml: 3,586; cpp: 2,624; ruby: 2,576; makefile: 2,443; sh: 2,312; python: 778; yacc: 764; ml: 763; awk: 260; csh: 186; php: 171; lex: 165; tcl: 44; java: 41; asm: 23; haskell: 17
file content (14 lines) | stat: -rw-r--r-- 717 bytes parent folder | download | duplicates (13) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
 
(in-package :alexandria)

(defun featurep (feature-expression)
  "Returns T if the argument matches the state of the *FEATURES*
list and NIL if it does not. FEATURE-EXPRESSION can be any atom
or list acceptable to the reader macros #+ and #-."
  (etypecase feature-expression
    (symbol (not (null (member feature-expression *features*))))
    (cons (check-type (first feature-expression) symbol)
          (eswitch ((first feature-expression) :test 'string=)
            (:and (every #'featurep (rest feature-expression)))
            (:or  (some #'featurep (rest feature-expression)))
            (:not (assert (= 2 (length feature-expression)))
                  (not (featurep (second feature-expression))))))))