Data commit

Task/Extend-your-language/Racket/extend-your-language.rkt

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+#lang racket
+;; define a new syntax
+(define-syntax-rule
+  ;; this is the new syntax we want, in sexpr syntax:
+  (if2 condition1isTrue condition2isTrue
+       bothConditionsAreTrue
+       firstConditionIsTrue
+       secondConditionIsTrue
+       noConditionIsTrue)
+  ;; and this is the syntax that implements it:
+  (if condition1isTrue
+    (if condition2isTrue
+      bothConditionsAreTrue
+      firstConditionIsTrue)
+    (if condition2isTrue
+      secondConditionIsTrue
+      noConditionIsTrue)))
+;; ... and that's all you need -- it now works:
+(define (try x y)
+  (displayln (if2 (< x 10) (< y 10)
+                  "Both small"
+                  "First is small"
+                  "Second is small"
+                  "Neither is small")))
+(try 1 1)   ; Both small
+(try 1 10)  ; First is small
+(try 10 1)  ; Second is small
+(try 10 10) ; Neither is small