sicp-ex-4.8

meteorgan
  
  
 (define (named-let? expr) (and (let? expr) (symbol? (cadr expr)))) 
 (define (named-let-func-name expr) (cadr expr)) 
 (define (named-let-func-body expr) (cadddr expr)) 
 (define (named-let-func-parameters expr) (map car (caddr expr))) 
 (define (named-let-func-inits expr) (map cadr (caddr expr))) 
 (define (named-let->func expr) (list 'define  
                                                                (cons (named-let-func-name expr)  
                                                                          (named-let-func-parameters expr)) 
                                                                (named-let-func-body expr))) 
 (define (let->combination expr) 
         (if (named-let? expr) 
                 (sequence->exp 
                         (list 
                                 (named-let->func expr) 
                                 (cons (named-let-func-name expr) (named-let-func-inits expr)))) 
                 (cons (make-lambda (let-vars expr) (list (let-body expr))) 
                           (let-inits expr))))