Add as-int.

project.clj

@@ -1,4 +1,4 @@
-(defproject useful "0.8.0-alpha1"
+(defproject useful "0.8.0-alpha2"
   :description "A collection of generally-useful Clojure utility functions"
   :dependencies [[org.clojure/clojure "1.4.0-beta1"]
                  [org.clojure/tools.macro "0.1.1"]]

src/useful/datatypes.clj

@@ -1,10 +1,18 @@
 (ns useful.datatypes
   (:use [useful.map :only [position into-map update]]
+        [useful.utils :only [invoke]]
         [useful.fn :only [fix]])
   (:require [clojure.string :as s])
   (:import (java.lang.reflect Field)
            (clojure.lang Compiler$LocalBinding)))
 
+(defn as-int [x]
+  (condp invoke x
+    integer? x
+    string? (Integer/parseInt x)
+    float? (int x)
+    nil))
+
 (let [munge-ops [["?" "_QMARK_"]
                  ["!" "_BANG_"]
                  ["-" "_"]]

test/useful/datatypes_test.clj

@@ -1,6 +1,13 @@
 (ns useful.datatypes-test
   (:use clojure.test useful.datatypes))
 
+(deftest test-as-int
+  (are [in out] (= (as-int in) out)
+       "1" 1
+       2 2
+       4.5 4
+       nil nil))
+
 (defrecord Test [a b c])
 (defrecord Other [dash-thing question? bang!])
 (record-accessors Test Other)