From: Ramakrishnan Muthukrishnan <vu3rdd@gmail.com>
Date: Sat, 31 Dec 2011 17:57:25 +0000 (+0530)
Subject: bug fix for let* to handle the body properly
X-Git-Url: https://git.rkrishnan.org/pf/content/fr.html?a=commitdiff_plain;h=a7bf1376fa635c6868752c6458442aef5da63327;p=sicp.git

bug fix for let* to handle the body properly
---

diff --git a/src/sicp/metacircular2.rkt b/src/sicp/metacircular2.rkt
index f08b5a1..a2dd8d4 100644
--- a/src/sicp/metacircular2.rkt
+++ b/src/sicp/metacircular2.rkt
@@ -176,9 +176,9 @@
 ;; let*
 (define (let*->nested-lets lexpr)
   (match lexpr
-    [`(let* (,first-binding ,rest-bindings ...) ,body)
-     `(let (,first-binding) ,(let*->nested-lets `(let* ,rest-bindings ,body)))]
-     [`(let* () ,body) body]))
+    [`(let* (,first-binding ,rest-bindings ...) ,body ..1)
+     `(let (,first-binding) ,(let*->nested-lets `(let* ,rest-bindings ,@body)))]
+     [`(let* () ,body ..1) `(let () ,@body)]))
 
 ;; internal definitions
 (define (scan-out-definitions body)
@@ -191,7 +191,7 @@
 
 ;; eval
 (define (eval exp env)
-  ;; (display (format "~s~%" exp))
+  (display (format "~s~%" exp))
   (match exp
     [(? self-evaluating? exp) exp]
     [(? variable? exp) (lookup-variable-value exp env)]
@@ -204,7 +204,7 @@
     [`(begin ,exp ...) (eval-sequence exp env)]
     [`(cond ,clauses ...) (eval (cond->if clauses) env)]
     [`(let ,bindings ,body ..1) (eval (let->combination exp) env)]
-    [`(let* ,bindings ,body) (eval (let*->nested-lets exp) env)]
+    [`(let* ,bindings ,body ..1) (eval (let*->nested-lets exp) env)]
     [(list f x ...) (apply (eval f env) (list-of-values x env))]
     [_ (error "unable to evaluate expression -- EVAL " exp)]))