Re:Facebook Launches Flow, Static Type Checker for JavaScript
by lmm on Wednesday November 19, 2014 @08:24AM
(#8629836)
> This looks like such a better step in the right direction than than the types of tools MS and Google have been putting out. Dynamically discerning the underlying code, and allowing optional type annotation works _with_ javascript, as opposed to attempting to turn js into a completely different (and weakened) language.
Typescript (from MS) sounds a lot like what you describe - it doesn't change Javascript, it just adds types to it (and makes some ES6 features available), and it puts a lot of work into playing nice with the wider JS ecosystem (e.g. via the definitelytyped project, which integrates type definitions for most popular "third-party" javascript libraries).
> That said, I am curious what solutions this solves that isn't already solved by enforcing good code coverage. Full disclaimer, the largest js projects I've worked on were in the tens of thousands of lines, not hundreds of thousands, but type checking just seemed completely unnecessary provided a good coding guide and test coverage were maintained and enforced.
Perfect testing can do everything a type system can. But a type system can do it with less programmer effort, much lower maintenance overhead, and in a standard form that makes it easier to maintain. So you can do the same thing but cheaper - or, more realistically for how software is developed in most companies, you can get better reliability for the same engineering budget.
Typescript (from MS) sounds a lot like what you describe - it doesn't change Javascript, it just adds types to it (and makes some ES6 features available), and it puts a lot of work into playing nice with the wider JS ecosystem (e.g. via the definitelytyped project, which integrates type definitions for most popular "third-party" javascript libraries).
> That said, I am curious what solutions this solves that isn't already solved by enforcing good code coverage. Full disclaimer, the largest js projects I've worked on were in the tens of thousands of lines, not hundreds of thousands, but type checking just seemed completely unnecessary provided a good coding guide and test coverage were maintained and enforced.
Perfect testing can do everything a type system can. But a type system can do it with less programmer effort, much lower maintenance overhead, and in a standard form that makes it easier to maintain. So you can do the same thing but cheaper - or, more realistically for how software is developed in most companies, you can get better reliability for the same engineering budget.