Parse, Don't Validate (2019)

This principle is how pydantic[0] utterly revolutionized my python development experience. I went from constantly having to test functions in repls, writing tons of validation boilerplate, and still getting TypeErrors and NoneTypeErrors and AttributeErrors left and right to like...just writing code. And it working! Like one time I wrote a few hundred lines of python over the course of a day and then just ran it... and it worked. I just sat there shocked, waiting for the inevitable crash and traceback to dive in and fix something, but it never came. In Python! Incredible.

[0] https://pydantic-docs.helpmanual.io/

I've found this to be simply a matter of experience, not tooling. As the years go by I find the majority of my code just working right - never touched anything like pydantic or validation boilerplate for my own code, besides having to write unit tests as an afterthought at work to keep the coverage metric up.

I agree. I'm often baffled by some developers who seem to think dynamic typing is a minefield that inevitably goes wrong all the time. I note these are almost always Javascript programmers, though. In practice, experience developers in dynamic languages like Python, Lisp etc. rarely make such errors. The number of bugs we deal with that would have been caught early by static typing are vanishingly small.

The best argument I've heard for doing type annotation is for documentation purposes to help future devs. But I don't completely buy this either. I touch new codebases all the time and I rarely spend much time thinking about what types will be passed. I can only assume it comes with experience.

Type annotation actually ends up taking a hell of a long time to do and is of questionable benefit if some of the codebase is not annotated. People spend sometimes hours just trying to get the type checker to say OK for code that actually works just fine!

It's okay if you're working on a blog site, less so if you're working on an air-planes autopilot.

JPL sent Lisp to space https://flownet.com/gat/jpl-lisp.html