Ep 12: ReaderT is good for the environment

If you're new to this series I make videos about functional programming, category theory, Scala, Haskell, Lisp and other functional languages.

This video continues with an expression evaluator program and the theme of Monad Transformers. I implemented and used the WriterT monad a couple of videos ago, so this time I build the ReaderT monad and explain what it is used for. In this case we stop using Scala 3 context functions (from episode 1) to thread some data through our program, and instead use the ReaderT monad. Once we create the new classes we simply change the return type of our program and follow the red squiggly lines (errors) to guide us to a working example of ReaderT.

You can get the code for this video here:

https://github.com/justinhj/evalexample/blob/video12/src/main/scala/livevideos/Video12.scala

Scala stuff by me
Video editing by Jamie
Intro music "Functional Justin Intro 1" by me

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Видео Ep 12: ReaderT is good for the environment канала Functional Justin