add more information on types

Author: eerio

README.md

@@ -18,8 +18,9 @@ This repository contains an interpreter for the [Latte](https://www.mimuw.edu.pl
 
 The Latte Interpreter is designed to execute programs written in the Latte programming language. It takes Latte source code as input and runs it, producing the corresponding output. The interpreter performs lexical analysis, parsing, and static type checking, followed by the execution of the input program. It is built using Haskell, leveraging the power and expressiveness of the functional programming paradigm.
 
-What do I personally like in this implementation? The types! Look at this:
-https://github.com/eerio/latte-interpreter/blob/0f80c0cff471a4c5a941c2dda57667bc3a5f2eb1/app/Interpreter.hs#L56-L72
+What do I personally like in this implementation? The types! Please take a look at this:
+https://github.com/eerio/latte-interpreter/blob/0f80c0cff471a4c5a941c2dda57667bc3a5f2eb1/app/Interpreter.hs#L56-L80
+Beautiful, isn't it? The nontrivial thing here is the type of the [monadic transformer](https://en.wikipedia.org/wiki/Monad_transformer) (`IM a`) - as we know, monadic transformers aren't commutative, so that the type itself had to be somehow engineered. A different type could also work, but the rest of the implementation wouldn't be as elegant as now.
 
 
 ## Features

app/Interpreter.hs

@@ -53,19 +53,27 @@ instance Show Exc where
 
 instance Exception Exc
 
+-- Loc type is an abstraction for indexing the cells of our memory abstraction
 type Loc = Int
+-- Env is the mapping from a variable/function/etc. name to a memory cell with it's value
 type Env = Map Ident Loc
+-- all the types supported by my version of Latte
 data Val = ValVoid
   | ValInt !Integer
   | ValBool !Bool
   | ValStr !String
   | ValFun !Env ![ArgC] !BlockC
   deriving Show
+-- abstraction of the memory: maps a cell number to a true value it holds
 type Store = Map Loc Val
+-- type of stdout
 type Log = Data.Sequence.Seq String
 
+-- the most important thing: the type of `execution` of the interpreter.
 type IM a = ExceptT Exc (RWST Env Log Store Identity) a
 
+-- a simple `malloc` function for our abstraction of the memory :)
+-- yes, the numbers grow indefinitely - NOP for this task
 alloc :: Store -> Loc
 alloc store = case Map.maxViewWithKey store of
   Nothing -> 0