Feels like Python

Productive

Run directly from source

Fast

Compile to C when ready to ship

Familiar

Syntax you recognize

Newton is still under development. The above points are aspirational.

A Functional Imperative Mix

How does one add immutability to a language in which the established idioms center on imperative for loops, without starting a cultural revolution? I have been mulling over this question and think I found a good answer.

Existential Types in Practical Terms

It turns out that pattern matching on Python-style tuples requires existential types. This is the second time I encounter them, so I figured it is a good opportunity to show how they arise in practise.

Type Checking Variadic Functions

Python’s print function is difficult to type check because it takes an arbitrary number of arbitrary arguments. We cannot give it a fixed number of type parameters, like other polymorphic functions. How can we accomodate it in a statically typed language?

First Milestone Reached

I am now able to compile small but useful Newton programs that exercise the full feature set to Python! This is a major breakthrough because until now there was always something that would break when you tried something more complex.

Splintering into Dialects on Purpose

Newton will follow Python except when there is a strong reason not to. This statement contradicts something I wrote earlier, that generators will be immutable. But now I’m beginning to think I want both behaviors. I don’t mean making mutation optional, I mean two separate languages, one with mutation and one wholly without.

Adoption and Python Compatibility

When I started generating Python, I only thought of it as a stepping stone towards generating machine code or C. But over time, I realized the ability to generate Python is valuable in itself, just like Typescript does for Javascript. The question is, what degree of compatibility should I aim for?

Handwritten Generators

Before I start generating C, I want to be able to loop over generator expressions. Having to iterate using C-style loops would be such an anticlimax. But there is a lot of work before I get there and I want to validate the approach first.

Why compile to C?

I mentioned previously that I am targetting C but did not give a reason. Why not use LLVM instead, or go straight to machine code?

Compiling Pattern Matching

I haven’t had much time for Newton since the last blog post, but I was able to get past something I have been working on for a while recently. I can now lower match statements to decision trees.

Generators

Without generators Newton would not feel very pythonic at all, so I consider it a must-have for the first public release.