let, let* and named let in scheme.

lets.scm

#lang racket

(define-syntax let1
  (syntax-rules ()
    ((let1 ((var val) ...) expr)
       ((lambda (var ...) expr) val ...))))


(define-syntax let1*
  (syntax-rules ()
    ((let1* ((var1 val1) (var2 val2) ...) expr)
       ((lambda (var1) (let* ((var2 val2) ...) expr)) val1))
    ((let1* () expr) expr)))


(define-syntax namedlet
  (syntax-rules (g)
    ((namedlet name ((var val) ...) expr)
       (((lambda (g) (lambda (var ...) ((g g) var ...))) 
         (lambda (g) (lambda (var ...) 
                       ((lambda (name) expr) (g g))))) val ...))))