refactor

beautiful-racket-demo/basic-demo-3/expr.rkt

@@ -30,7 +30,12 @@
 
 (define-macro (b-func FUNC-ID ARG ...)
   #'(if (procedure? FUNC-ID)
-        (let ([result (FUNC-ID ARG ...)])
+        (convert-result (FUNC-ID ARG ...))
+        (raise-line-error
+         (format "expected ~a to be a function, got ~v"
+                 'FUNC-ID FUNC-ID))))
+
+(define (convert-result result)
   (cond
     [(number? result) (b-expr result)]
     [(string? result) result]
@@ -38,6 +43,3 @@
     [else
      (raise-line-error
       (format "unknown data type: ~v" result))]))
-        (raise-line-error
-         (format "expected ~a to be a function, got ~v"
-                 'FUNC-ID FUNC-ID))))