In general you should complete the exercises in the master branch. There is a solution branch with ... guess what...
Choose your adventure below
The aim is:
- Gain practice/confidence in handling errors.
- Gain practice weilding monads (all the exercises can be solved using generic monad or applicative functor methods!).
Complete the exercises in: com.rea.error.ErrorExercises
There are a series of tests that you need to make pass in ErrorExercisesSpec.
Run them with ./sbt test
We can represent the result of a function that may give us an error as "either an error or a result". We choose to use the scala "Either" class to hold this result type. Together with the Cats functional type-classes to provide us with the Monad and Applicative instances for Either, along with other useful type-classes.
Either forms a right-biased monad (since scala 2-12), which gives us all the richness of monad transformers and combinators to help us work with our errors. It is also an applicative functor, which gives us additional methods (sequence / transform).
In these exercises we first define AppError : a case class to hold our errors.
Then we define a type alias ErrorOr[A], that represents our return type of "Either an error or a result".
We then practice creating, combining and transforming our results.
The aim is:
- Gain practice/confidence in encoding using the circe library
- Gain an understanding of how circe is doing this.
Complete the exercises in: com.rea.json.CirceEncodingExercises
There are a series of tests that you need to make pass in CirceEncodingExercisesSpec
Run them with ./sbt test
The aim is:
- Gain practice/confidence in decoding using the circe library
- Gain an understanding of how circe is doing this.
Complete the exercises in: com.rea.json.CirceDecodeExercises
There are a series of tests that you need to make pass in CirceDecodeExercisesSpec
Run them with ./sbt test