Add String Interpolation With Quoted Strings as a reasonml til

reason/string-interpolation-with-quoted-strings.md

@@ -0,0 +1,35 @@
+# String Interpolation With Quoted Strings
+
+Stapling strings together with the `++` operator can be tedious and clunky.
+If you have string variables that you'd like to interpolate, you can piece
+them together much more easily using [quoted
+strings](https://reasonml.github.io/docs/en/string-and-char.html#quoted-string).
+
+We can get close to a solution with the standard quoted string syntax.
+
+```reason
+let greeting = (greetee) => {
+  {|Hello, $(greetee)!|}
+};
+
+Js.log(greeting("World")); // => "Hello, $(greetee)!"
+```
+
+This isn't quite right though. We have to take advantage of a preprocessing
+hook provided by
+[Bucklescript](https://bucklescript.github.io/docs/en/common-data-types.html#interpolation).
+The `j` hook supports unicode and allows variable interpolation.
+
+```reason
+let greeting = (greetee) => {
+  {j|Hello, $(greetee)!|j}
+};
+
+Js.log(greeting("World")); // => "Hello, World!"
+```
+
+To use this pre-processor we have to include `j` in the quoted string like
+so `{j|...|j}`.
+
+See a [live example
+here](https://reasonml.github.io/en/try.html?reason=DYUwLgBA5gTi4EsB2UIF4IApbzPAlOgHwQDeAUBGQFYA+AEiMMAPYA0EAJNnOAQIS1qAX3LCA3OXIApAM4A6VlB65kygEQB1FjGAATdfnzigA).