Scalaz TupleOps

In this post we’ll look at TupleOps and the goodies it provides to work with Tuples. There’s no TupleOps.scala file in the GitHub repo because the file is generated by GenerateTupleW. You can see the code for TupleOps if you’re using an IDE like IntelliJ. There’s a number of TupleNOps classes like Tuple2Ops[A, B], etc. all the way to Tuple12Ops[A, B].

With that said, let’s jump into examples. We’ll look at what Tuple2Ops provides us. Everything is analogous to Tuple3Ops, etc. It’s just the number of arguments to the methods that will change.

Folding a Tuple

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@ import scalaz._
import scalaz._
@ import Scalaz._
import Scalaz._
@ (1, 2) fold( (_1, _2) => _1 + _2 )
res2: Int = 3

fold in Tuple2Ops takes a function which accepts 2 arguments i.e. equal to the arity of the tuple. Here, we’re folding the tuple and adding together its two Int elements but you can do whatever you want.

Converting to IndexedSeq

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@ (1, 2) toIndexedSeq
res3: collection.immutable.IndexedSeq[Int] = Vector(1, 2)

This one is self-explanatory. The tuple is converted to an IndexedSeq.

Mapping Elements in a Tuple

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@ (1, 2) mapElements(_1 => _1 * 2, _2 => _2 * 2)
res4: (Int, Int) = (2, 4)

mapElements in Tuple2Ops takes 2 functions as arguments, 1 for each element of the tuple. The functions are then applied to their corresponding elements and the result is returned as a Tuple. In the example above, we’re just multiplying both the elements by 2.

This is different from the map from the standard library. The map from the standard library only operates on the last element of the tuple. 

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@ (1, 2) map (_ * 2)
res5: (Int, Int) = (1, 4)

Conclusion

That’s the end of the post on TupleOps. TupleOps‘s convenience methods can be used to manipulate tuples easily.