Consider the fact that there are infinite programs. If you can handle print(“Hello world!”), I can give you print(“Hello world!0”). If you can handle print(“Hello world!0”), I can give you print(“Hello world!00”). And that's not just limited to statements about printing a string that contains “Hello world!”

x = "Hello world!"
print(x)

x = 1
y = 1
print(x + y)

• Crafting Interpreters, a book about making programming languages that first uses Java, then C
  
• Chapter 4 of SICP, which teaches how to implement Scheme in Scheme
  

TheAspiringHacker wrote:

Hi! I saw this post last night when your project could only handle “print(”Hello world!“)” and was going to respond, but I was busy with homework. I see that you've updated your project to print any arbitrary string. That's a good first step.

I was going to say something like:

Consider the fact that there are infinite programs. If you can handle print(“Hello world!”), I can give you print(“Hello world!0”). If you can handle print(“Hello world!0”), I can give you print(“Hello world!00”). And that's not just limited to statements about printing a string that contains “Hello world!”

Right now, when you parse a command, you require the argument of print to be inside double quotes. What if I wanted to do

x = "Hello world!"
print(x)

or even

x = 1
y = 1
print(x + y)

?

The big idea about programming and programming languages is the recursive nature of programs. Do you notice that in Scratch, scripts are comprised of smaller scripts? Scratch programs can be arbitrarily large, so in order to evaluate them, you must appeal to recursion and write a function that calls itself on the sub-programs.

In the 2.0 era, on my old account, I made a programming language that handles arbitrarily large programs with recursion: https://scratch.mit.edu/projects/103551203/ However, I found it unmaintainable because Scratch didn't provide me with enough abstractions, and I don't know if it still works in 3.0 (I don't make any guarantees).

I've been interested in programming language theory for a long time now and can talk a lot about it. I will direct you to the following resources:

• Crafting Interpreters, a book about making programming languages that first uses Java, then C
  
• Chapter 4 of SICP, which teaches how to implement Scheme in Scheme
  

If you don't know one of these languages, pick one and learn it. There is an educational value in learning different programming languages, especially ones that are different from what you may know. If you're most fluent in Scratch, learning one of these languages will give you a bigger idea about what programming is about, and some of the concepts you learn will even help you implement your own languages. (e.g. Java uses a virtual machine. What is that? Can you use a virtual machine for your own language, perhaps? What are the stack and heap? What is garbage collection?)

christo wrote:

Wow! Have you written any other programming language before? If so, what did you write it in? If something other than scratch then you might gain a lot of value from doing this first. If scratch is your first programming language then I think you can make a programming language in it as long as you start with the simplest thing that could possibly work and then step up towards Python gradually.