Refactoring if to match

One of the refactorings I find myself doing quite often in Scala is converting large branching if trees into an easy to read match statement. The reasoning is that it is much easier to read a match statement because it is like reading bullet points rather than trying to follow the flow of information through a tree of if statements.

Before you complain, I realize there are other ways to refactor a tree of if-statements but I find the match statements the easiest to reason about and the quickest to write with the least amount of boiler plate.

Here is an example where I need to see if the file is dirty and needs to be regenerated, if it is clean or if some one has modified the generated file (which results in a CONFLICT).

1. object State extends Enumeration {
2.   final val DIRTY, CLEAN, CONFLICT = Value
3. }
6. if( !pom.file.exists ){
7.   DIRTY;
8. }else if (checksum.file.exists) {
9.   val sha = new String(MessageDigest.getInstance("SHA").digest( pom.slurp.getBytes ))
10.   if( sha == checksum.slurp ) CLEAN
11.   else DIRTY
12. } else {
13.   CONFLICT
14. }
18. pomFile(massFile) match {
19.   case (pom, checksum) if (!pom.file.exists) => DIRTY
20.   case (pom, checksum) if (!checksum.file.exists) => CONFLICT
21.   case (pom, checksum) => {
22.     val sha = new String(MessageDigest.getInstance("SHA").digest( pom.slurp.getBytes ))
23.     if( sha == checksum.slurp ) CLEAN
24.     else DIRTY
25.   }
26. }