types: new implementation using vectors with metadata and the new type selector function

1 files changed, 26 insertions, 3 deletions

diff --git a/src/clojure/contrib/types/examples.clj b/src/clojure/contrib/types/examples.clj
index 26421697..4e801f75 100644
--- a/src/clojure/contrib/types/examples.clj
+++ b/src/clojure/contrib/types/examples.clj
@@ -22,10 +22,10 @@
 			(leaf :c))))
 
 (defn depth
-  [#^tree t]
+  [t]
   (match t
     empty-tree  0
-    (leaf n)    1
+    (leaf _)    1
     (node l r)  (inc (max (depth l) (depth r)))))
 
 (depth empty-tree)
@@ -34,7 +34,7 @@
 ;
 ; Algebraic data types with multimethods: Haskell-style functors
 ;
-(defmulti fmap (fn [f s] (class s)))
+(defmulti fmap (fn [f s] (type s)))
 
 ; Sequences
 (defmethod fmap clojure.lang.ISeq
@@ -46,6 +46,11 @@
   [f v]
   (into [] (map f v)))
 
+; Maps
+(defmethod fmap clojure.lang.IPersistentMap
+  [f m]
+  (into {} (for [[k v] m] [k (f v)])))
+
 ; Trees
 (defmethod fmap tree
   [f t]
@@ -56,6 +61,7 @@
 
 (fmap str '(:a :b :c))
 (fmap str [:a :b :c])
+(fmap str {:a 1 :b 2 :c 3})
 (fmap str a-tree)
 
 ;
@@ -79,3 +85,20 @@
 (foo-to-int (bar 3 3 1))
 (foo-to-int (bar 0 3 1))
 (foo-to-int (bar 10 20 30))
+
+;
+; Value accessors are defined only for algebraic data types that have
+; exactly one constructor. get-values is defined if there is at least
+; one argument in the constructor; it returns a vector of values.
+; get-value is defined only for exactly one argument, it returns
+; the value directly.
+;
+
+(get-value (bar 1 2 3))  ; fails
+(get-values (bar 1 2 3))
+
+(deftype sum-type
+  (sum x))
+
+(get-value (sum 42))
+(get-values (sum 42))