Merge pull request #130 from nickzuber/master

Continuations

readme.md

@@ -21,6 +21,7 @@ __Table of Contents__
 * [Currying](#currying)
 * [Auto Currying](#auto-currying)
 * [Function Composition](#function-composition)
+* [Continuation](#continuation)
 * [Purity](#purity)
 * [Side effects](#side-effects)
 * [Idempotent](#idempotent)
@@ -176,6 +177,37 @@ const floorAndToString = compose((val) => val.toString(), Math.floor) // Usage
 floorAndToString(121.212121) // '121'
 ```
 
+## Continuation
+
+At any given point in a program, the part of the code that's yet to be executed is known as a continuation.
+
+```js
+const printAsString = (num) => console.log(`Given ${num}`)
+
+const addOneAndContinue = (num, cc) => {
+  const result = num + 1
+  cc(result)
+}
+
+addOneAndContinue(2, printAsString) // 'Given 3'
+```
+
+Continuations are often seen in asynchronous programming when the program needs to wait to receive data before it can continue. The response is often passed off to the rest of the program, which is the continuation, once it's been received.
+
+```js
+const continueProgramWith = (data) => {
+  // Continues program with data
+}
+
+readFileAsync('path/to/file', (err, response) => {
+  if (err) {
+    // handle error
+    return
+  }
+  continueProgramWith(response)
+})
+```
+
 ## Purity
 
 A function is pure if the return value is only determined by its