In this chapter, we were armed with the theoretical foundations of effects, what they are, and why they are needed. We took a look at some examples of effects types which are frequently encountered in practice. We have seen how the Future type abstracts away asynchronous computations. We also looked at the Either type, which is similar to Try, but allows alternative representations for errors. Finally, we covered the Reader effect type, which abstracts away the effect of dependency. We also saw that flatMap is a typical pattern among effect types, which abstracts away the sequential composition of side effecting computations, and the effects of which are rectified into effect types.
In the next chapter, we'll have a look at how to generalize patterns of working with effect types.