haskell functional programming as a liberal arts

In my case, I decided to create a type Effect, which currently has two constructors, but which I can easily extend if I create statetransformers with novel effects. Because this chooseAction function needs to return values of one and the same type, all my monadic operations must have the same type. Even though they do quite different things, I think I need them to have the same type because of the chooseAction function (Line 232): Between different steps of the brainfuck program, the next instruction has to be read from the instruction tape and turned into an actual executable statetransformer. In lines 149-188, I implement the eight brainfuck operations as state-transforming operations. The question is: Is it okay to make one type for which I implement ALL the functionality, or am I better off splitting it into two types and duplicating the code for the shared instructions (most are shared)? Is there a idiomatic way to have types 'inherit' from other types? For example, the operation 'increment byte at pointer' is only needed for the data tape, while 'seek next matching bracket' is only needed for the instruction tape (Lines 1-100). The functionality of the two tapes overlap, but not completely. I use this type for both the data tape and the brainfuck program itself, the instruction tape. I made a type Tape with a pointer which can be shifted and read from / written to. In particular, I am unsure about the following points:

The goal is to afterwards use StateT instead of State and combine that with IO, so that I properly learn to use monad transformers. This implementation is lacking any IO, because I wanted to create a simple, baseline implementation of stateful computation. But I am sure there are many more eyes on which I am blind, so please point out where I go wrong or miss more elegant solutions. It was eye-opening in some regards, because I finally used and designed monadic operations by myself. This project is a brainfuck interpreter, for which I used nothing but the wiki article on brainfuck (i.e., no foreign design or code, apart from whileM).

In my previous project, I made a JSON parser, but relied heavily on guidance from a university course. I am rather new to haskell, and could use some feedback on my code and the decisions I had to make.

Haskell functional programming as a liberal arts