Merge pull request #169 from kilianmh/feat/typecase-let

Feat: add typecase-let, etypecase-let

control-flow.lisp

@@ -521,6 +521,18 @@ Burson."
      (ecase ,var
        ,@cases)))
 
+(defmacro typecase-let ((var expr) &body cases)
+  "Like (let ((VAR EXPR)) (typecase VAR ...)), with VAR read-only."
+  `(let1 ,var ,expr
+     (typecase ,var
+       ,@cases)))
+
+(defmacro etypecase-let ((var expr) &body cases)
+  "Like (let ((VAR EXPR)) (etypecase VAR ...)), with VAR read-only."
+  `(let1 ,var ,expr
+     (etypecase ,var
+       ,@cases)))
+
 (defmacro comment (&body body)
   "A macro that ignores its body and does nothing. Useful for
 comments-by-example.

package.lisp

@@ -145,6 +145,8 @@
    #:ecase-let
    #:cond-let
    #:case-let
+   #:typecase-let
+   #:etypecase-let
    #:bcond
    #:comment
    #:example

tests/control-flow.lisp

@@ -197,6 +197,27 @@
     (ecase-let (x 17)
       (0 x) (1 (1+ x)))))
 
+(test typecase-let
+  (is (eql 2
+	   (typecase-let (x 2)
+	     (string 20)
+	     (integer x))))
+  (is (string= "test-here"
+	       (typecase-let (y "test")
+		 (integer "not")
+		 (string (concatenate 'string y "-here"))))))
+
+(test etypecase-let
+  (is (eql 2
+	   (etypecase-let (x 'asdf)
+	     (string 20)
+	     (integer x)
+	     (symbol 2))))
+  (signals type-error
+    (etypecase-let (y 'test-symbol)
+      (integer "not")
+      (string (concatenate 'string y "-here")))))
+
 (test comment
   (is-false (comment "This is a comment")))