(library (ikarus apply)
  (export apply)
  (import 
    (except (ikarus) apply)
    (ikarus system $pairs)
    (ikarus system $stack))

  (define apply
    (let ()
      (define (err f ls)
        (if (procedure? f)
            (error 'apply "not a list")
            (error 'apply "~s is not a procedure" f)))
      (define (fixandgo f a0 a1 ls p d)
        (cond
          [(null? ($cdr d))
           (let ([last ($car d)])
             ($set-cdr! p last)
             (if (and (procedure? f) (list? last))
                 ($$apply f a0 a1 ls)
                 (err f last)))]
          [else (fixandgo f a0 a1 ls d ($cdr d))]))
      (define apply
        (case-lambda
          [(f ls) 
           (if (and (procedure? f) (list? ls))
               ($$apply f ls)
               (err f ls))]
          [(f a0 ls)
           (if (and (procedure? f) (list? ls))
               ($$apply f a0 ls)
               (err f ls))]
          [(f a0 a1 ls)
           (if (and (procedure? f) (list? ls))
               ($$apply f a0 a1 ls)
               (err f ls))]
          [(f a0 a1 . ls)
           (fixandgo f a0 a1 ls ls ($cdr ls))]))
      apply)))