In this video we will see how useful it is to make less decisions in the DSLs and allow the interpreters to drive ALL the necessary design details in a type-safe way so that the DSLs and our programs can remain untouched when the interpreters change. The commit from this (technically from the next) video is here: https://github.com/DevInsideYou/tagless-final/commit/f266873ffe98952e1167537ed9256b9172e19242 The code for the entire series is here: https://github.com/DevInsideYou/tagless-final The Cats' Functor Hierarchy is here: https://cdn.rawgit.com/tpolecat/cats-infographic/master/cats.svg Structure and Interpretation of Computer Programs (SICP): https://web.mit.edu/alexmv/6.037/sicp.pdf Oleg Kiselyov's website: http://okmij.org/ftp/ The "Typed Tagless Final Interpreters" paper from Oleg Kiselyov's website: http://okmij.org/ftp/tagless-final/course/lecture.pdf If you decide to follow along with the paper, this might help: https://gist.github.com/OlivierBlanvillain/48bb5c66dbb0557da50465809564ee80 The "Extensible Denotational Language Specifications" paper by Robert Cartwright and Matthias Felleisen: https://pdfs.semanticscholar.org/321c/a540ce3a9beed5db54c8f8047191b8185c50.pdf This video is part of the following playlist:    • Tagless Final   Table of Contents: 00:00 Introduction 01:00 Adding F[_] to the DSL 06:03 Division with hardcoded Either 08:28 Issues with hardcoding Either into division 09:47 Relation to the todo app 11:54 Adding F[_] to the interpreters 30:26 Adding F[_] to the programs 31:07 Adding F[_] to the main 34:34 Id Website: https://devinsideyou.com/ Patreon: https://patreon.devinsideyou.com/ Discord: https://discord.devinsideyou.com/ Telegram: https://telegram.devinsideyou.com/ Twitter: https://twitter.devinsideyou.com/ GitHub: https://github.devinsideyou.com/ LBRY: https://lbry.devinsideyou.com/ Install scripts: https://install.devinsideyou.com/ Giter8 templates: https://g8.devinsideyou.com/ Spotify concentration playlist: https://code.radio.devinsideyou.com/ Cheers and Happy Coding! #tf #Scala #tutorial