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call-arguments-limit

call-arguments-limit Constant Variable

Constant Value:

An integer not smaller than 50 and at least as great as the value of lambda-parameters-limit, the exact magnitude of which is implementation-dependent.

Description:

The upper exclusive bound on the number of arguments that may be passed to a function.

See Also:

lambda-parameters-limit, multiple-values-limit

Data and Control

Expanded Reference: call-arguments-limit​

Inspecting the Value​

The value of call-arguments-limit is implementation-dependent but must be at least 50 according to the standard. It represents the upper exclusive bound on the number of arguments that may be passed to a function.

;; Check the implementation's limit
call-arguments-limit
=> 1073741824

;; The standard guarantees at least 50
(>= call-arguments-limit 50)
=> T

Relationship to Other Limits​

call-arguments-limit is related to lambda-parameters-limit and multiple-values-limit. All three constrain different aspects of function calls.

;; Compare the limits
(list call-arguments-limit
      lambda-parameters-limit
      multiple-values-limit)
=> (1073741824 1073741824 1073741824)

;; call-arguments-limit bounds what you can pass via apply
;; This is fine for small lists:
(apply #'+ '(1 2 3 4 5))
=> 15

Defensive Use with apply​

When using apply with dynamically constructed argument lists, it is good practice to be aware of call-arguments-limit to avoid hitting the ceiling.

;; A safe wrapper that checks before calling apply
(defun safe-apply (fn args)
  (if (< (length args) call-arguments-limit)
      (apply fn args)
      (error "Too many arguments: ~D (limit is ~D)"
             (length args) call-arguments-limit)))

(safe-apply #'+ '(1 2 3))
=> 6