Add Break Out Of A While Loop as a reasonml til

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_683 TILs and counting..._
+_684 TILs and counting..._
 
 ---
 
@@ -501,6 +501,7 @@ _683 TILs and counting..._
 
 ### ReasonML
 
+- [Break Out Of A While Loop](reason/break-out-of-a-while-loop.md)
 - [Defining Variants With Constructor Arguments](reason/defining-variants-with-constructor-arguments.md)
 - [Exhaustive Pattern Matching Of List Variants](reason/exhaustive-pattern-matching-of-list-variants.md)
 - [Helping The Compiler Help Us With Variants](reason/helping-the-compiler-help-us-with-variants.md)

reason/break-out-of-a-while-loop.md

@@ -0,0 +1,27 @@
+# Break Out Of A While Loop
+
+The `while` construct is a great way to loop indefinitely. You may
+eventually want to break out of the loop. For that, you are going to need to
+invalidate the _while condition_. One way of going about this is creating a
+mutable ref, changing it from true to false when a certain condition is met.
+
+```reasonml
+let break = ref(true);
+
+while (break^) {
+    switch (Unix.readdir(currentDir)) {
+    | exception End_of_file => break := false
+    | item => print_endline(item);
+    }
+};
+```
+
+Here we have a mutable ref called `break` which starts as `true`. This is
+our _while condition_. Its actual value can be referenced by appending the
+`^` character -- hence `break^`. Once a certain condition is met inside our
+`while` block, we can set `break` to `false` using the `:=` operator.
+
+The above code snippet can be seen in full details
+[here](https://github.com/jbranchaud/basic-ls-reason-native/blob/master/src/Index.re).
+
+[source](https://reasonml.github.io/docs/en/imperative-loops.html#tips-tricks)