Day 27 | 30 Days of AI Prompts

Try it!

This runs as a Python CLI — clone the repo and run it locally to try it out.

Source Code

memory = {}
while True:
    line = input("> ")
    words = line.split()
    if words[0] == 'set':
        name = words[1]
        value = words[3]
        memory[name] = int(value)
    elif words[0] == 'print':
        name = words[1]
        print(memory[name])
    elif words[0] == 'add':
        var1 = words[1]
        var2 = words[3]
        print(memory[var1] + memory[var2])
    elif words[0] == 'subtract':
        var1 = words[1]
        var2 = words[3]
        print(memory[var1] - memory[var2])
    elif words[0] == 'exit':
        break
    else:
        print("Unknown command. Available commands:")
        print("  set <name> to <value>       — store a variable")
        print("  print <name>               — display a variable")
        print("  add <name1> and <name2>    — add two variables")
        print("  subtract <name1> and <name2> — subtract two variables")
        print("  exit                       — quit")

Description

Context: I wanted to understand what it takes to build a programming language from scratch — even a very basic one. Keeping the feature set minimal meant I could focus on the core loop: read a line, parse the command, execute it.

Challenges: Designing a readable command syntax that was still easy to parse with simple string splitting. The four commands — set, print, add, subtract — all follow a consistent word-position pattern so the interpreter stays straightforward.

Result: A working REPL-style interpreted language in one Python file. You can store integer variables, display them, and do addition and subtraction between named variables. Example session:

set x to 10
set y to 5
add x and y → 15
subtract x and y → 5

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