Merge branch 'zero-sumtypes' of https://github.com/hellerve/Carp into hellerve-zero-sumtypes

core/Maybe.carp

@@ -66,4 +66,7 @@ It is the inverse of [`just?`](#just?).")
    (if (null? a)
      (Nothing)
      (Just @(Pointer.to-ref a))))
+
+  (doc zero "returns `Nothing`.")
+  (defn zero [] (Nothing))
 )

docs/core/Maybe.html

@@ -502,6 +502,26 @@ a value using <code>zero</code> if a <code>Nothing</code> is passed.</p>
 
                 </p>
             </div>
+            <div class="binder">
+                <a class="anchor" href="#zero">
+                    <h3 id="zero">
+                        zero
+                    </h3>
+                </a>
+                <div class="description">
+                    defn
+                </div>
+                <p class="sig">
+                    (λ [] (Maybe a))
+                </p>
+                <pre class="args">
+                    (zero)
+                </pre>
+                <p class="doc">
+                    <p>returns <code>Nothing</code>.</p>
+
+                </p>
+            </div>
             <div class="binder">
                 <a class="anchor" href="#zip">
                     <h3 id="zip">

test/maybe.carp

@@ -63,6 +63,11 @@
                 (or-zero (the (Maybe Int) (Nothing)))
                 "or-zero works on Nothing"
   )
+  (assert-equal test
+                &(Nothing)
+                &(the (Maybe Int) (zero))
+                "zero works"
+  )
   (assert-equal test
                 &(Result.Success 1)
                 &(to-result (Just 1) @"error")