Update README.md

Author: julianjumper

README.md

@@ -3,7 +3,26 @@ Simplify Data Workflows by Combining Programming and Data Operations! <br>
 Designed to work with data stream operations directly on common data formats such as JSON and CSV. <br>
 *YADL* is a Turing-complete language and was created in a group at university. Thanks to all of them. This repository is a re-upload.
 
-## Example
+## Table of Contents
+1. [Introduction](#intro)
+    1. [Example](#example)
+    2. [Anonymous Functions](#anonymous)
+    3. [Commong Bugs](#bugs)
+2. [Quick Start/Installation](#start)
+3. [Build Instructions](#build)
+    1. [Prerequisites](#pre)
+    2. [Building in Terminal/Shell](#build_sh)
+    3. [Building in intellij IDEA](#build_idea)
+4. [Testing of Code](#testing)
+    1. [Unit testing](#unit)
+    1. [Testing with pytest](#python)
+
+
+## Introduction <a name="intro" />
+
+> Beyond basic queries, SQL struggles with complex data manipuiation. APIs often return data in JSON format, requiring additional parsing. YADL bridges the gap, offering built-in functionality for both - write less code, analyze more effectively. It's a programming language that allows to parse different file types (json, csv, etc.) with a singe load function and to work with data operations on it.
+
+### Example <a name="example"></a>
 
 ```js
 weather_data = load("./weather-data.json", "json") // open json file
@@ -23,26 +42,62 @@ print3("Is Bern the best city?: idk, im a computer")
 print3("Has Bern continuous data?:")
 index = 1
 continuous_data = true
-while (index < len(bern) && continuous_data) {
-    if (bern[index-1]["day"] +1 != bern[index]["day"]) {
+while (index < len(bern) and continuous_data) {
+    if (bern[index-1]["day"] +1 != bern[index+0]["day"]) {
         continuous_data = false
     }
+    
     index = index + 1
 }
 print3(continuous_data)
 ```
 Assuming there is the file `weather-data.json`, this file will use functions, loops and if-statements to analyze the data in the JSON. This is of course only a small demonstration. <br>
-Functions, that are not specifically declared in this example are inbuilt functions. For all in-built functions (with description), [click here](spec/stdlib/iterator methods.md). <br>
+Functions, that are not specifically declared in this example are inbuilt functions. For all in-built functions (with description), [click here](https://github.com/julianjumper/yadl/blob/main/spec/stdlib/iterator%20methods.md). <br>
 Please keep in mind, that this project was created in a short period of time. This has not reach its full potential. The most important idea we had in mind, is to load the data chunk-wise so that not all data needs to be stored in memory.
 
-## Build Instructions
+### Anonymous functions <a name="anonymous"></a>
+
+We also have anonymous functions! <br>
+This code from the example uses one:
+```js
+has_freezing_days = (city) => {
+    return check_any(city, (item) => item["temp"] < 0)
+}
+print3("Is it freezing?", has_freezing_days(bern)
+```
+Notice this line: `check_any(city, (item) => item["temp"] < 0)` <br>
+Right there, we use the anonymous function `(item) => item["temp"] < 0)` which returns true, if attribute "temp" of the passed object "item" is below 0. <br>
+Is this example, it is passed to one of our in-built function from the standard library `check_any` (["see here"](https://github.com/julianjumper/yadl/blob/main/spec/stdlib/iterator%20methods.md) for more information). It is a higher-order function, which takes the anonymous function as an argument. 
+
+But we can also immediately call anonymous functions instead:
+```js
+print3("2 + 1:", ((a,b) => a+b)(2,1))
+```
+
+### Common bugs: <a name="bugs"></a>
+- In the example, you might have noticed the `index+0` in the if-statement. This is because the parser expects a value of an operation. I will fix it when I have time! <br>
+  btw, `index+0` is an easy fix - in our group we made fun of this bug by using an anonymous identity function and passing the wanted value: `((i) => i)(index)`🤪
+- After an if-statement, you have to insert a blank line - also an issue with the parser.
+
+## Quick Start/Installation <a name="start"></a>
+
+### Download JAR
+
+- download the JAR from this GitHub repository
+
+### Running a `.yadl` file
+Run this command:
+`java -jar <path-to-jar> <path-to-yadl>`
+path-to-jar is the path to the downloaded jar-file and path-to-yadl the path to your yadl program. You can download and use the test file `fancy-tests/wather-data.yadl`.
+
+## Build Instructions <a name="build"></a>
 
-### Prerequisites
+### Prerequisites <a name="pre"></a>
 
 - [Scala 3.X](https://www.scala-lang.org/download/)
 - Recent Java SDK (openjdk 22 for example)
 
-### Building in Terminal/Shell
+### Building in Terminal/Shell <a name="build_sh"></a>
 
 Run the following commands in the project root.
 
@@ -63,7 +118,7 @@ sbt "run args..."
 
 The quotes are neccessary here because otherwise they would be interpreted as a new command from sbt.
 
-### Building in intellij IDEA
+### Building in intellij IDEA <a name="build_idea"></a>
 
 #### Installing Plugins
 
@@ -82,16 +137,16 @@ Once done hit 'Apply' or 'OK' to finish the task setup.
 
 Now you should be able to build/run/package/... the project depending on what you chose as a task.
 
-### Unit testing and Python Script testing
+### Unit testing and Python Script testing <a name="testing"></a>
 
-#### Unit testing
+#### Unit testing <a name="unit"></a>
 
 Similar to building in the terminal you execute the following for the scala unit tests:
 ```sh
 sbt test
 ```
 
-#### Python Script testing
+#### Python Script testing <a name="python"></a>
 
 These tests involve a bit more work to be run.
 For the duration of these steps I assume you are at the root of the project.