Implement numeric validation.

Closes #130.

invoke.js

@@ -5,6 +5,8 @@ var util = require('util')
 var slice = [].slice
 var interrupt = require('./interrupt')
 
+function isNumeric (n) { return !isNaN(parseFloat(n)) && isFinite(n) }
+
 module.exports = cadence(function (async, source, env, argv, io, main) {
     var options = {}
 
@@ -59,7 +61,11 @@ module.exports = cadence(function (async, source, env, argv, io, main) {
             }
         })
     }
-    options.validate = function (test) {
+    options.numeric = function () {
+        this.validate.apply(this, [ '%s is not numeric' ].concat(slice.call(arguments))
+                                                         .concat(isNumeric))
+    }
+    options.validate = function () {
         var vargs = slice.call(arguments)
         var format = vargs.shift()
         var test = vargs.pop()

t/arguable/run.t.js

@@ -122,6 +122,12 @@ var prove = cadence(function (async, assert) {
     }), function (error) {
         assert(error.context.message, 'level is not an integer', 'validate')
     })
+    run(path.join(__dirname, 'sub.js'), {}, [ 'run', '-p', 3, '-l', 'x' ],  {
+    }, cadence(function (async, options) {
+        options.numeric('processes', 'level')
+    }), function (error) {
+        assert(error.context.message, 'level is not numeric', 'numeric')
+    })
     run(__filename, {}, [],  {
     }, cadence(function (async, options) {
         assert(options.format('ordered', 'this', 'that'), 'First that then this.', 'ordered format')
@@ -141,4 +147,4 @@ var prove = cadence(function (async, assert) {
     io.events.emit('SIGINT')
 })
 
-require('proof')(24, prove)
+require('proof')(25, prove)