X-Git-Url: https://git.rkrishnan.org/?p=sicp.git;a=blobdiff_plain;f=src%2Fsicp%2Fex4_54.rkt;fp=src%2Fsicp%2Fex4_54.rkt;h=79dcb0c9e20357b29ef5a9cb5b04083915bb298b;hp=0000000000000000000000000000000000000000;hb=205b4712a8e8c88693b184030143ff513ec26a92;hpb=c3062a9e8691e9c067b69ec24a728c746520b310

diff --git a/src/sicp/ex4_54.rkt b/src/sicp/ex4_54.rkt
new file mode 100644
index 0000000..79dcb0c
--- /dev/null
+++ b/src/sicp/ex4_54.rkt
@@ -0,0 +1,15 @@
+#lang racket
+
+(define (assert? expr) (tagged-list? expr 'assert))
+
+(define (assert-predicate expr) (first (rest expr)))
+
+(define (analyze-assert exp)
+  (let ((pproc (analyze (assert-predicate exp))))
+    (lambda (env succeed fail)
+      (pproc env
+             (lambda (pred-value fail2)
+               (if (not (true? pred-value))
+                   (fail)
+                   (succeed 'ok fail2)))
+             fail))))
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