Add concat.

doc/API.md

@@ -15,6 +15,7 @@
     - [Channel.from(callback | iterable | stream.Readable[, mapfn [, thisArg]]) -> read-only Channel](#channelfromcallback--iterable--streamreadable-mapfn--thisarg---read-only-channel)
       - [Examples](#examples-1)
   - [Channel Object](#channel-object)
+    - [concat(...arguments) -> Channel](#concatarguments---channel)
     - [every(callbackfn[, thisArg]) -> async Boolean](#everycallbackfn-thisarg---async-boolean)
     - [filter(callbackfn[, thisArg]) -> Channel](#filtercallbackfn-thisarg---channel)
     - [forEach(callbackfn[, thisArg]) -> async](#foreachcallbackfn-thisarg---async)
@@ -202,6 +203,12 @@ const fromStream = Channel.from(
 
 ## Channel Object
 
+### concat(...arguments) -> Channel
+
+When the `concat` method is called with zero or more arguments, it returns a
+channel containing the values of the channel followed by the channel values of
+each argument in order.
+
 ### every(callbackfn[, thisArg]) -> async Boolean
 
 `callbackfn` should be a function that accepts one argument and returns a value

lib/index.js

@@ -103,6 +103,26 @@ const Channel = function(length = 0) {
 
   const readOnly = Object.freeze(
     Object.assign(Object.create(prototype), {
+      concat: (...args) => {
+        const output = Channel();
+
+        (async () => {
+          await readOnly.forEach(output.push);
+
+          for (let index = 0; index < args.length; index++) {
+            const arg = args[index];
+
+            await (Channel.isChannel(arg)
+              ? arg.forEach(output.push)
+              : output.push(arg));
+          }
+
+          output.close();
+        })();
+
+        return output;
+      },
+
       every: async (callbackfn, thisArg) => {
         for (;;) {
           const value = await readOnly.shift();

test/index.js

@@ -213,6 +213,15 @@ describe(`Channel object`, function() {
     });
   });
 
+  it(`concat`, async function() {
+    assert.deepEqual(
+      await Channel.of(0, 1, 2)
+        .concat(Channel.of(3, 4, 5), 6)
+        .values(),
+      [0, 1, 2, 3, 4, 5, 6]
+    );
+  });
+
   it(`every`, async function() {
     const even = number => number % 2 === 0;
     assert(!await Channel.of(0, 1, 2).every(even));