Ruby has optional type checking. What do you think the testing regime is about?
It's a compiler that is built for each project with types specific to the domain problem being solved.
Language type checking misses the point. The types I want to check, and the extent I want to check them, are in the spec files.
Go type inference, for example, is deeply primitive and an awful lot of Go code seems to spend its time implementing duck typing via work arounds. It looks an awful lot like dependency injection for the 2010s.
> Language type checking misses the point. The types I want to check, and the extent I want to check them, are in the spec files.
It's worth incorporating a way to express these things directly into the language proper. That way all your tools will understand them (e.g. automated refactoring will already know what needs to be updated) and you can talk about them in the language.
> Go type inference, for example, is deeply primitive and an awful lot of Go code seems to spend its time implementing duck typing via work arounds.
Yeah, Go is the exception. It's profoundly and proudly ignorant of 65 years of language design progress. If Go were the only language type system I had access to I'd think language type checking was pointless too.
Go is a terrible example of a statically typed language. Now that is an example of a bunch of people not learning from the past - ie. the entire lineage of ML-based languages!
A rich type system lets you mold and shape the types to fit nicely over your domain, effectively becoming a machine-verified DSL for your business problem. It will catch flaws in your mental model before you even begin to write tests or an implementation, and is a cheap way of sketching out your ideas and great documentation to have over the lifetime of your project. Of course you can't fit it exactly, so you need a smattering of spec tests, and probably some property-based tests for good measure to fill in the gaps.
It's a compiler that is built for each project with types specific to the domain problem being solved.
Language type checking misses the point. The types I want to check, and the extent I want to check them, are in the spec files.
Go type inference, for example, is deeply primitive and an awful lot of Go code seems to spend its time implementing duck typing via work arounds. It looks an awful lot like dependency injection for the 2010s.