Merge pull request #128 from thinker1990/chapter05

add exercise 5.13
thinker1990 · Jul 29, 2019 · 0b36f3a · 0b36f3a
2 parents 33eb3d9 + c777e34
commit 0b36f3a
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/chapter05/5_13.scm b/chapter05/5_13.scm
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+;; Solution from: http://community.schemewiki.org/?sicp-ex-5.13
+
+(define (lookup-register name)
+  (let ((val (assoc name register-table)))
+    (if val 
+        (cadr val)
+        (begin (allocate-register name)
+               (lookup-register name)))))