scala better syntax for map getOrElse

Question

is there a better way to write the code below?

val t = map.get('type).getOrElse(""); 
if (t != "") "prefix" + t;

be interested in inline code something like

val t = map.get('type).getOrElse("").????

Answer 1

Map has its own getOrElse method, so you can just write the following:

val t = map.getOrElse('type, "")

Which accomplishes the same thing as the definition of t in your first example.

---

To address your comment: If you know your map will never contain the empty string as a value, you can use the following to add the "prefix":

map.get('type).map("prefix" + _).getOrElse("")

Or, if you're using Scala 2.10:

map.get('type).fold("")("prefix" + _)

If your map can have "" values, this version will behave a little differently than yours, since it will add the prefix to those values. If you want exactly the same behavior as your version in a one-liner, you can write the following:

map.get('type).filter(_.nonEmpty).map("prefix" + _).getOrElse("")

This probably isn't necessary, though—it sounds like you don't expect to have empty strings in your map.

Answer 2

It's also worth noting that, in certain cases, you can replace multiple common .getOrElse usages with one .withDefaultValue call.

val map = complexMapCalculation().withDefaultValue("")

val t = map('type)

I wouldn't say this is something that should be done every time, but it can be handy.