Merge pull request pixie-lang#333 from stuarth/misc-fns

heyLu · heyLu · commit 5b03225dde10 · 2015-06-15T08:37:51.000+02:00
add select-keys, rand-int, some?
diff --git a/pixie/stdlib.pxi b/pixie/stdlib.pxi
@@ -552,6 +552,11 @@ returns true"
 (defn rem [num div]
   (-rem num div))
 
+(defn rand-int
+  {:doc "random integer between 0 (inclusive) and n (exclusive)"}
+  [n]
+  (rem (rand) n))
+
 (defn =
   {:doc "Returns true if all the arguments are equivalent. Otherwise, returns false. Uses
 -eq to perform equality checks."
@@ -946,6 +951,16 @@ If further arguments are passed, invokes the method named by symbol, passing the
   (fn [v]
     (transduce ordered-hash-reducing-fn v)))
 
+(defn select-keys
+  {:doc "Produces a map with only the values in m contained in key-seq"}
+  [m key-seq]
+  (with-meta
+    (transduce
+     (comp (filter (fn [k] (contains? m k)))
+           (map (fn [k] [k (get m k)])))
+     conj {} key-seq)
+    (meta m)))
+
 (defn keys
   {:doc "If called with no arguments returns a transducer that will extract the key from each map entry. If passed
    a collection, will assume that it is a hashmap and return a vector of all keys from the collection."
@@ -1411,6 +1426,10 @@ The new value is thus `(apply f current-value-of-atom args)`."
 (defn nil? [x]
   (identical? x nil))
 
+(defn some? [x]
+  {:doc "true if x is not nil"}
+  (not (nil? x)))
+
 (defn fnil [f else]
   (fn [x & args]
     (apply f (if (nil? x) else x) args)))
diff --git a/tests/pixie/tests/test-stdlib.pxi b/tests/pixie/tests/test-stdlib.pxi
@@ -189,6 +189,16 @@
     (t/assert= (set (vals v)) #{1 2 3})
     (t/assert= (transduce (vals) conj! v) (vals v))))
 
+(t/deftest test-select-keys
+  (let [m ^{:k :v} {:a 1 :b 2}]
+    (t/assert= (select-keys m [:a :b]) m)
+    (t/assert= :v
+               (-> (select-keys m [:a])
+                   meta
+                   :k))
+    (t/assert= (select-keys m [:a :not-found]) {:a 1})
+    (t/assert= (select-keys m nil) {})
+    (t/assert= (select-keys {} [:a]) {})))
 
 (t/deftest test-empty
   (t/assert= (empty '(1 2 3)) '())
@@ -273,6 +283,10 @@
   (t/assert= (every? even? []) true)
   (t/assert= (every? odd? []) true))
 
+(t/deftest test-rand-int
+  (let [vs (repeatedly 10 #(rand-int 4))]
+    (t/assert (every? #(and (>= % 0) (< % 4)) vs))))
+
 (t/deftest test-some
   (t/assert= (some even? [2 4 6 8]) true)
   (t/assert= (some odd?  [2 4 6 8]) false)
