featurep (feature-expression)

feature-expression -- an atom or a list of atoms

a boolean

Returns t if the argument feature-expression matches the state of the *features* list and nil if it does not. The argument feature-expression can be any atom or list acceptable to the reader macros #+ and #-.

 (featurep :sbcl) => T
 (featurep (and :linux :sbcl :windows)) => NIL
 (featurep (or :linux :sbcl :windows)) => T