Added first session notes

README.md

@@ -1,10 +1,18 @@
-# learning-languages
+
+# Learning new languages and documenting my journey
 
 Repository which documents my journey in learning new languages.
 
 Currently learning:
+<style>
+    #rust {
+        filter: invert(1);
+    }
+</style>
 <p align="center">
+  <span id="rust">
   <img src="https://raw.githubusercontent.com/devicons/devicon/master/icons/rust/rust-original.svg" alt="Rust" width="50" height="50"/>
+  </span>
   <img src="https://raw.githubusercontent.com/devicons/devicon/master/icons/haskell/haskell-original.svg" alt="Haskell" width="50" height="50"/>
   <img src="https://raw.githubusercontent.com/devicons/devicon/master/icons/swift/swift-original.svg" alt="Swift" width="50" height="50"/>
   <img src="https://dashboard.snapcraft.io/site_media/appmedia/2021/01/coq.png" alt="Coq" width="50" height="50"/>

coq/README.md

@@ -1,8 +1,8 @@
 <p align = "center">
-    <img src = "https://upload.wikimedia.org/wikipedia/commons/d/d8/Coq_logo.png" width = "100">
+    <img src = "https://calebstanford.com/img/2018/coq-vector-logo/coq-logo-large.png" width = "200">
 </p>
 
-# Learn Coq with me
+# Introduction
 <a href = "https://github.com/alhassy/CoqCheatSheet/blob/master/CheatSheet.pdf">
     <img src = "https://img.shields.io/badge/-CheatSheet-blue">
 </a>
@@ -18,12 +18,12 @@ When I feel confident enough, I will film a 1-2h tutorial on Coq and attach it t
 <!-- - [Software Foundations](https://softwarefoundations.cis.upenn.edu/current/index.html) by Benjamin C. Pierce et al. -->
 
 ## ToC
-- [Learn Coq with me](#learn-coq-with-me)
+- [Introduction](#introduction)
   - [ToC](#toc)
   - [Motivation](#motivation)
   - [Installation](#installation)
 - [Basic Coq](#basic-coq)
-  - [Introduction](#introduction)
+  - [Introduction](#introduction-1)
   - [Comment on semantics](#comment-on-semantics)
     - [Type theory](#type-theory)
   - [Basic Concepts + Syntax](#basic-concepts--syntax)

haskell/README.md

@@ -0,0 +1,40 @@
+<p align = "center">
+<img src="https://raw.githubusercontent.com/devicons/devicon/master/icons/haskell/haskell-original.svg" alt="Haskell" width="200"/>
+</p>
+
+# Introduction
+After miserably failing my Functional Programming exam and some soul searching, I realized that I never really learned Haskell nor did I ever really understand functional programming. So, I decided to learn Haskell properly. This repository will document my journey in learning Haskell.
+
+With the help of some friends!
+
+This is going to be structured in a different way than my other repositories. I will have a `sessions` folder where I will document my thought process and the things I learned while during my "lessons". Maybe do Haskell notebooks? I don't know yet.
+
+This is the larger, more general README, which will house the main takeaways/revelations of the sessions.
+
+## ToC
+- [Introduction](#introduction)
+  - [ToC](#toc)
+- [Books and resources](#books-and-resources)
+  - [13th of March - Introduction](#13th-of-march---introduction)
+
+# Books and resources
+- [Haskell Programming from first principles](http://haskellbook.com/)
+- [Learn you a Haskell for great good](http://learnyouahaskell.com/)
+
+
+## [13th of March - Introduction](sessions/13_03/notes.md)
+
+Big question:
+
+> Why is the singly-linked list the most common data structure in functional programming?
+
+Because it is the simplest recursive data structure. It is a recursive data structure because it is defined in terms of itself. It is a singly-linked list because it has a head and a tail. The head is the first element of the list and the tail is the rest of the list.
+
+<p align="center">
+    <img src="assets/list.png" alt="lists" width="700"/>
+</p>
+
+> But why not a tree?
+
+The tree is simply too complex. Linked lists are easy.
+

haskell/sessions/13_03/notes.md

@@ -0,0 +1,132 @@
+
+## Progress report - confidence scale
+In the first meeting, we went through the structure of my exam on a very surface level. 
+I reached the conclusion that, although I have a vague idea of what the topics are, I don't have a deep understanding of them. All of my knowledge is very superficial.
+
+Hence, this progress report will be a preamble of each session, where I will list the topics and the corresponding confidence I have in them.
+
+The scale of my confidence in the topics:
+1. 😎 - Very confident
+2. 😊 - Confident
+3. 😐 - Can solve, no intuition
+4. 😕 - No idea 
+
+| Topic | Description | Confidence |
+|-------|-------------|------------|
+| Signatures | Checking whether the expression types are correct | 😊 |
+| Programming | Writing code to solve an algorithmic problem | 😐 |
+| Higher order functions | Demonstrate understanding of higher order functions, usually by chaining them | 😐 |
+| List comprehensions | Demonstrate understanding of list comprehensions | 😐 |
+| Recursion/infinite lists | Infinitely generating lists, usually by recursion and/or list comprehensions | 😕 |
+| ADTs | Algebraic Data Types, usually defining a data type and writing functions that operate on it | 😕 |
+| Proof on lists | Proving properties of functions that operate on lists | 😕 |
+| Proof on trees/ADTs | Proving properties of functions that operate on trees or ADTs | 😕 |
+
+## Basics
+
+### Signatures
+
+Example given - the `.` operator a.k.a. $f \circ g = f(g(x))$
+
+```haskell
+(.) :: (b -> c) -> (a -> b) -> a -> c
+f . g = \x -> f (g x)
+```
+Why? Because the type of `f` is `b -> c`, the type of `g` is `a -> b`, and the type of `x` is `a`. Hence, the type of the output is `c`.
+
+
+### Stack and heap
+**What's the stack?**
+> The stack is a data structure that stores information about the active subroutines of a computer program. It is used to store the return address of the function, the local variables of the function, and the parameters passed to the function. 
+> This is like CPU registers, but for functions.
+
+**What's the heap?**
+> The heap is a region of memory that is not managed automatically for you. This is a large pool of memory from which you can request blocks of memory.
+> This is like the RAM of the computer.
+
+**What's the difference between the stack and the heap?**
+> The stack is used for static memory allocation and the heap is used for dynamic memory allocation, both stored in the computer's RAM.
+i.e. in C:
+```c
+int main() {
+    int x = 5; // Stack
+    int* y = malloc(sizeof(int)); // Heap
+}
+```
+
+**What's the difference between the stack and the heap in Haskell?**
+> In Haskell, the stack is used for function calls and the heap is used for storing data.
+> This is because Haskell is a lazy language, so it doesn't evaluate the function calls immediately. Instead, it stores them in the stack and evaluates them when needed.
+> The heap is used for storing data because Haskell is a functional language, so it doesn't have mutable variables. Hence, it stores the data in the heap.
+> This is why Haskell is a pure language.
+
+
+### Recursion
+
+Recursion in Haskell is very similar to recursion in other languages. The only difference is that Haskell is a lazy language, so it doesn't evaluate the recursion immediately. Instead, it stores the recursion in the stack and evaluates it when needed.
+
+Tail recursion is a special case of recursion where the recursive call is the last thing in the function. 
+
+Example of non-tail recursion:
+```haskell
+fib :: Int -> Int
+fib 0 = 0
+fib 1 = 1
+fib n = fib (n-1) + fib (n-2)
+```
+
+To make the `fib` function tail recursive, we can use an accumulator[^1]
+```haskell
+fib :: Int -> Int
+fib n = go n 0 1
+    where
+        go 0 a b = a
+        go n a b = go (n-1) b (a+b)
+```
+
+### `map, foldr, foldl, filter, zip`
+
+These are higher order functions in Haskell. They are used to operate on lists.
+
+`map` applies a function to each element of a list.
+```haskell
+map :: (a -> b) -> [a] -> [b]
+map f [] = []
+map f (x:xs) = f x : map f xs
+```
+
+<p align="center">
+    <img src="folds.png" alt="folds" width="700"/>
+</p>
+
+`foldr` is a right fold. It is used to reduce a list to a single value.
+```haskell
+foldr :: (a -> b -> b) -> b -> [a] -> b
+foldr f z [] = z
+foldr f z (x:xs) = f x (foldr f z xs)
+```
+
+`foldl` is a left fold. It is used to reduce a list to a single value.
+```haskell
+foldl :: (b -> a -> b) -> b -> [a] -> b
+foldl f z [] = z
+foldl f z (x:xs) = foldl f (f z x) xs
+```
+
+`filter` is used to filter a list based on a predicate.
+```haskell
+filter :: (a -> Bool) -> [a] -> [a]
+filter p [] = []
+filter p (x:xs) = if p x then x : filter p xs else filter p xs
+```
+
+`zip` is used to combine two lists into a list of tuples.
+```haskell
+zip :: [a] -> [b] -> [(a, b)]
+zip [] _ = []
+zip _ [] = []
+zip (x:xs) (y:ys) = (x, y) : zip xs ys
+```
+
+
+[^1]: This is a common pattern in functional programming. The idea is to pass an accumulator to the function and update it in each recursive call. This is to "circumvent" immutability by introducing a way to store the "state" of the function.

rust/README.md

@@ -0,0 +1,28 @@
+<style>
+    /* Invert rust logo */
+    #rust img {
+        filter: invert(1);
+    }
+</style>
+
+<p align = "center">
+<span id=rust>
+<img src="https://raw.githubusercontent.com/devicons/devicon/master/icons/rust/rust-original.svg" alt="Rust" width="200"/>
+</span>
+</p>
+
+# Introduction
+On my journe to memory safety and due to lots of ridicule from my friends about daily-driving Python, I am currently looking for a systems programming language that is memory safe and has a good ecosystem (i.e. is not hated by everyone). In other words, I am looking for a *practically useful* language that is not Python or C++.
+
+Rust seems to be the perfect fit for this. This repository will document my journey in learning Rust.
+
+The process of learning this language is going to be quite different from my other repositories. I will try to design an embedded project in Rust, instead of focusing on algorithmic problems (i.e. practical problems). This will help me understand the language better and also give me a taste of what it is like to work with Rust in a real-world scenario.
+
+I'm going to try and ***actually document*** my process instead of my usual cheat-sheet style. 
+
+## ToC
+- [Introduction](#introduction)
+  - [ToC](#toc)
+
+
+

swift/README.md

@@ -2,6 +2,14 @@
 <img src="https://raw.githubusercontent.com/devicons/devicon/master/icons/swift/swift-original.svg" alt="Swift" width="250"/>
 </p>
 
+# Introduction 
+I watched a Swift lecture by an apple guy at FOSDEM 2025. It was pretty cool. Inspired me to think about memory safety, and, needless to say, learn Swift.
+
+
+## ToC
+
+- [Introduction](#introduction)
+  - [ToC](#toc)
 - [General Notes](#general-notes)
   - [Swift project](#swift-project)
     - [Package.swift](#packageswift)
@@ -27,12 +35,11 @@
 - [Project-specific Notes](#project-specific-notes)
   - [Most likely teammates for Software engineering](#most-likely-teammates-for-software-engineering)
 
+
 # General Notes
 There are **NO** semicolons in Swift. The language is designed to be concise and readable. Very pythonic in that sense.
 
-Swift is a statically-typed language. This means that the type of a variable is known at compile time. This is in contrast to dynamically-typed languages like Python, where the type of a variable is determined at runtime.
+Swift is a statically-typed language. This means that the type of a variable is known at compile time. This is in contrast to dynamically-typed languages like Python, where the type of a variable is determined at runtime. It deals with memory by using Automatic Reference Counting (ARC). This means that the compiler automatically manages memory for us.
-
-Swift deals with memory by using Automatic Reference Counting (ARC). This means that the compiler automatically manages memory for you. This is in contrast to languages like C and C++, where you have to manually manage memory.
 
 Swift is a multi-paradigm language. This means that it supports multiple programming paradigms, such as object-oriented programming, functional programming, and procedural programming. We'll get into this later.