Add support for aliases

lib/extractors.js

@@ -7,7 +7,12 @@ const {partition, log} = require('./utils');
 
 const extractors = {
     * TypeAlias(node) {
-        const schema = yield node.right;
+        let schema = yield node.right;
+
+        if (typeof schema === 'string') {
+            schema = {type: schema};
+        }
+
         schema.name = yield node.id;
 
         yield provide(schema);

tests/references.js

@@ -1,4 +1,4 @@
-type A = {};
+type A = string;
 
 type Type = {
     a: A,
@@ -21,9 +21,8 @@ class Class {
 // ###
 ({
     A: {
-        type: 'record',
+        type: 'string',
         name: 'A',
-        fields: [],
     },
     Type: {
         type: 'record',