(library (srfi n11)
  (export let-values)
  (import (except (rnrs base) let-values let*-values))

;; *R6RS*: let[*]-values is subsumed by the let[*]-values of (rnrs base).
;; The reference implementation is provided here anyway for non-R6RS
;; systems, or systems which would like to use this as their
;; implementation of let[*]-values.

;; SRFI 11 Reference Implementation
;; http://srfi.schemers.org/srfi-11/srfi-11.html

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; This code is in the public domain.

(define-syntax let-values
  (syntax-rules ()
    ((let-values (?binding ...) ?body0 ?body1 ...)
     (let-values "bind" (?binding ...) () (begin ?body0 ?body1 ...)))
    
    ((let-values "bind" () ?tmps ?body)
     (let ?tmps ?body))
    
    ((let-values "bind" ((?b0 ?e0) ?binding ...) ?tmps ?body)
     (let-values "mktmp" ?b0 ?e0 () (?binding ...) ?tmps ?body))
    
    ((let-values "mktmp" () ?e0 ?args ?bindings ?tmps ?body)
     (call-with-values 
       (lambda () ?e0)
       (lambda ?args
         (let-values "bind" ?bindings ?tmps ?body))))
    
    ((let-values "mktmp" (?a . ?b) ?e0 (?arg ...) ?bindings (?tmp ...) ?body)
     (let-values "mktmp" ?b ?e0 (?arg ... x) ?bindings (?tmp ... (?a x)) ?body))
    
    ((let-values "mktmp" ?a ?e0 (?arg ...) ?bindings (?tmp ...) ?body)
     (call-with-values
       (lambda () ?e0)
       (lambda (?arg ... . x)
         (let-values "bind" ?bindings (?tmp ... (?a x)) ?body))))))

(define-syntax let*-values
  (syntax-rules ()
    ((let*-values () ?body0 ?body1 ...)
     (begin ?body0 ?body1 ...))

    ((let*-values (?binding0 ?binding1 ...) ?body0 ?body1 ...)
     (let-values (?binding0)
       (let*-values (?binding1 ...) ?body0 ?body1 ...)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
) ; end library