js-proposal-algebraic-effects VS exhaustive

I have to admit: you're perfectly right here. React of course always relied on mutable state in it's implementation – just so we don't have to. I derailed a lot here to keep this funny thread going ;) I'm still not with you on your definition of "functional", since you treated it synonymously with "purely functional". Functional means just made by applying and composing functions, and react UI is created exactly like that. There is an awesome algebraic effects proposal[1], which will hopefully will be added to JavaScript one day, then react will make use of it to become purely functional.

1: https://github.com/macabeus/js-proposal-algebraic-effects

Super interesting, there is a proposal to add this to JavaScript and several languages that use this, unison, koka & eff. I had no idea this was even a thing!

Ok I was wrongly assuming that panic was expecting an error type, in fact it's an interface{}.

> Your use of exceptions for flow control (i.e. goto) is considered harmful

Exceptions are a way to delegate error handling to the caller by giving them informations about the unexpected behavior. It implies that the expected behavior is the "happy path" (everything went well) and any deviations (errors) is unexpected.

This is far from a goto because you can have `try/finally` blocks without catch (or defer in golang).

Also, exceptions are just a kind of algebraic effects that do not resume. There was a proposal to JS for this: https://github.com/macabeus/js-proposal-algebraic-effects

This is also easier to test. assertRaises(ErrorType, func() { code... })

Almost every Go library I've seen just return an error (which is just a string), you'd need to parse it to assert that the correct error is returned in special conditions.

This is an analyzer that will catch this: https://github.com/nishanths/exhaustive

I believe it's in golangci-lint.

I agree linters in general are quite useful for Go though. The default suite from golangci-lint is quite good. I would also recommend enabling exhaustive if you're working with a codebase that uses "enums" (full disclosure, I contributed a bit to that project).

there’s a linter for exhaustive matching: https://github.com/nishanths/exhaustive

I tried to find that linter and found this: exhaustive

And in Go you'd use a linter, like this one.

this is AST go vet analyzer that performs just that: https://github.com/nishanths/exhaustive (too bad it can not do struct based enums..)

>> the main thing missing from Go is ADT's. After using these in Rust and Swift, a programming language doesn't really feel complete without them

What are the differences between an ADT (plus pattern matching i’d reckon?) in Rust/Swift vs the equiv in Go (tagged interfaces + switch statement)?

One has exhaustive matching at compile time, the other has a default clause (non exhaustive matching), although there’s an important nub here with respect to developer experience; it would be idiomatic in Go to use static analysis tooling (e.g. Rob Pike is on record saying that various checks - inc this one - don’t belong in the compiler and should live in go vet). I’ve been playing with Go in a side project and using golint-ci which invokes https://github.com/nishanths/exhaustive - net result, in both go and rust, i get a red line of text annotated at the switch in vscode if i miss a case.

Taking a step back, there isn’t a problem you can solve with one that you can’t solve with the other, or is there?

To take a step further back, why incomplete?

Use a linter.

For an exhaustive linter, were you referring to this? It looks pretty nice. If it's possible to check this with static analysis, is it something that could be in the compiler itself in the future?

https://github.com/nishanths/exhaustive

here, have fun. You’re gonna write some tests, make new types to satisfy interfaces for testing, and then wind up with branches for your test paths in your live code, but go for it, I guess. You know everything! I am but a simple blubbite, too dim, too dim to get it.