Add Two Ways To Find An Item In A List 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/).
 
-_724 TILs and counting..._
+_725 TILs and counting..._
 
 ---
 
@@ -540,6 +540,7 @@ _724 TILs and counting..._
 - [String Interpolation With Integers And Sprintf](reason/string-interpolation-with-integers-and-sprintf.md)
 - [String Interpolation With Quoted Strings](reason/string-interpolation-with-quoted-strings.md)
 - [Trying Out ReasonML In CodeSandbox](reason/trying-out-reasonml-in-codesandbox.md)
+- [Two Ways To Find An Item In A List](reason/two-ways-to-find-an-item-in-a-list.md)
 - [Wrapping A Component For Use In JavaScript](reason/wrapping-a-component-for-use-in-javascript.md)
 
 ### Ruby

reason/two-ways-to-find-an-item-in-a-list.md

@@ -0,0 +1,30 @@
+# Two Ways To Find An Item In A List
+
+The `List` module has the typical `find` function that you'd expect any
+enumerable type to include. It has a very similar `find_opt` function as
+well. The difference is in the return types.
+
+When using `List.find` you'll have to deal with the possibility of a
+`Not_found` exception.
+
+```reasonml
+switch (List.find(item => item.id == id, my_list)) {
+| exception Not_found => print_endline("Not found!")
+| item => print_endline("Found it: " ++ item.name)
+}
+```
+
+The `List.find_opt` function has a more familiar interface that doesn't
+require you to know the details of what exceptions could arise. All you want
+to know is if it was found or _not_. This is achieved by having an
+`option('a)` return type.
+
+```reasonml
+switch (List.find_opt(item => item.id == id, my_list)) {
+| None => print_endline("Not found!")
+| Some(item) => print_endline("Found it: " ++ item.name)
+}
+```
+
+See the [`List` module](https://reasonml.github.io/api/List.html) for more
+details.