Why This Matters
A Microsoft engineer's weekend code-golf project—cramming a Python-like interpreter into 1024 bytes of plain C—is a reminder of how much of a language's 'feel' comes from a small slice of its syntax. It's a hands-on teaching artifact: a recursive-descent interpreter stripped to globals and fixed arrays, in contrast to CPython's tokenize-AST-bytecode pipeline. For developers, it's an accessible way to demystify how interpreters actually work.
Key Takeaways
- Austin Z. Henley hand-wrote a Python-subset interpreter in 1024 bytes of C, with no macro tricks or library shortcuts.
- The original 512-byte target proved too small—a basic expression-and-if calculator already blew the budget, so the limit doubled.
- The design skips CPython's AST, optimization, and bytecode stages entirely, relying on a few global variables and a fixed-length array.
Austin Z. Henley I build tools for people [email protected]
@austinzhenley
github/AZHenley
Making a Python interpreter in 1024 bytes
9/6/2026
To feel human, I write code by hand on the weekends.
My latest challenge? Make a Python interpreter in 512 1024 bytes of good ole C code. Oh, and no macro shenanigans or library tomfoolery.
def buzz(): for n in range(101): if n % 15 == 0: print("FizzBuzz") else: if n % 3 == 0: print("Fizz") else: if n % 5 == 0: print("Buzz") else: print(n) buzz()
I probably can't fit all of the Python language into an interpreter that is only 1024 bytes of code. So what can I fit that will look like Python?
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