predicate-iterator

Conformance: SketchyLISP Core

Purpose: Turn a binary predicate into a variadic predicate.

Arguments:
P - predicate

Implementation:

(define (predicate-iterator p)
  (lambda (first . rest)
    (let ((fail (cons 'fail '())))
      (let
        ((comp
           (lambda (a b)
             (cond ((eq? a fail) fail)
               ((p a b) b)
               (else fail)))))
        (cond ((null? rest)
            (bottom '(too few arguments)))
          (else (neq? (fold-left comp first rest)
                      fail)))))))

Example:

((predicate-iterator eq?) 'foo 'foo 'foo) 
=> #t

See also:
<, =, char<?, char=?, string<?, string=?.