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Comment by ChadNauseam

3 months ago

I wish more languages would lean into having a really permissive compiler that emits a lot of warnings. I have CI so I'm never going to actually merge anything that makes warnings. But when testing, just let me do whatever I want!

GHC has an -fdefer-type-errors option that lets you compile and run this code:

    a :: Int
    a = 'a'
    main = print "b"

Which obviously doesn't typecheck since 'a' is not an Int, but will run just fine since the value of `a` is not observed by this program. (If it were observed, -fdefer-type-errors guarantees that you get a runtime panic when it happens.) This basically gives you the no-types Python experience when iterating, then you clean it all up when you're done.

This would be even better in cases where it can be automatically fixed. Just like how `cargo clippy --fix` will automatically fix lint errors whenever it can, there's no reason it couldn't also add explicit coercions of numeric types for you.

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ChadNauseam

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ninkendo  3 months ago

> I wish more languages would lean into having a really permissive compiler that emits a lot of warnings. I have CI so I'm never going to actually merge anything that makes warnings. But when testing, just let me do whatever I want!

I’d go even further and say I wish my whole development stack had a switch I can use to say “I’m not done iterating on this idea yet, cool it with the warnings.”

Unused imports, I’m looking at you… stop bitching that I’m not using this import line simply because I commented out the line that uses it in order to test something.

Stop complaining about dead code just because I haven’t finished wiring it up yet, I just want to unit test it before I go that far.

Stop complaining about unreachable code because I put a quick early return line in this function so that I could mock it to chase down this other bug. I’ll get around to fixing it later, I’m trying to think!

In rust I can go to lib.rs somewhere and #![allow(unused_imports,dead_code,etc)] and then remember to drop it by the time I get the branch ready for review, but that’s more cumbersome than it ought to be. My whole IDE/build/other tooling should have a universal understanding of “this is a work in progress please let me express my thoughts with minimal obstructions” mode.

  • ChadNauseam  3 months ago

    On the other hand, I can't count how many times I've written some code like

        let iteration_1_id = 10;
    dostuff(iteration_1_id);
    let iteration_2_id = 11; // warning, unused variable!!
    dostuff(iteration_1_id);

    and then spent 10 minutes debugging why iteration_2 wasn't working, when it would have been resolved instantly if I had paid attention to the warnings.

zaptheimpaler  3 months ago

Yeah this is my absolute dream language. Something that lets you prototype as easily as Python but then compile as efficiently and safely as Rust. I thought Rust might actually fit the bill here and it is quite good but it's still far from easy to prototype in - lots of sharp edges with say modifying arrays while iterating, complex types, concurrency. Maybe Rust can be something like this with enough unsafe but I haven't tried. I've also been meaning to try more Typescript for this kind of thing.

  • FacelessJim  3 months ago

    You should give Julia a shot. That’s basically that. You can start with super dynamic code in a REPL and gradually hammer it into stricter and hyper efficient code. It doesn’t have a borrow checker, but it’s expressive enough that you can write something similar as a package (see BorrowChecker.jl).

  • jimbokun  3 months ago

    Some Common Lisp implementations like SBCL have supported this style of development for many years. Everything is dynamically typed by default but as you specify more and more types the compiler uses them to make the generated code more efficient.

    • fc417fc802  3 months ago

      I quite like common lisp but I don't believe any existing implementation gets you anywhere near the same level of compile time safety. Maybe something like typed racket but that's still only doing a fraction of what rust does.