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In my experience with TS, its unsoundness was very frustrating. If you use it as a replacement for JSDoc where type ascriptions are more like recommendations, s
by raquo 9y ago
In my experience with TS, its unsoundness was very frustrating. If you use it as a replacement for JSDoc where type ascriptions are more like recommendations, sure, but I like to have more confidence than that in a type system. FlowType is much better in that regard. Scala.js has been the best for me so far.
- seanmcdirmid 9y agoI'm much more bothered by TS's lack of separate compilation (errors tend to cascade, but this is to be expected from a structural rather than nominal type system). The killer app for type systems has always been code completion.
- mafribe 9y agohas always been code completion. I disagree. Code completion is overrated and only of marginal importance in the production of high-quality code. The key advantages of types are: - Enabling ahead-of-time compilation resulting in efficient code. - Guarantees on the absence of specific classes of bugs. (This requires soundness.) - Aiding verification. Types provide a rough classification of program behaviour which drastically simplifies verification. If you don't have types, your program logic needs to make typing information explicit in assertions.
- seanmcdirmid 9y ago1. Nope, as proven that many people use JavaScript in the first place. 2. Type systems have always been super limited in the kinds of bugs they can eliminate, even with "soundness". 3. This sounds like a type theorists point that is completely detached from most programming experiences.
- mafribe 9y ago(1) I'm not sure I understand point. JS has long been without alternative, that's why JS has seen such a massive uptake. Moreover all JS alternatives, from TypeScript to Scala.js to Elm to Flow are adding types. Anyway JS's popularity is orthogonal to questions about efficient compilation. Types drastically simplify those, for you can work out at compile time how much memory needs to be allocated for each sub-expression of the program under execution. If you don't have types, you can only do that at run-time, and need extremely complicated JIT compiler technology to make this moderately performant. (2) Sure. Still extremely helpful, all the more so, the bigger the software. If you don't have types to do this, you will have to find those bugs by testing -- much more labour intensive. (3) Detached, maybe, but still true. To paraphrase Sutton's law: I'm detached from the toils of contemporary bread/butter programmers and look at verification because that's where the interesting open problems are.
- boubiyeah 9y agoI have a feeling you're talking about an old version of typescript. Versions 2.2+ (currently 2.3.2) are sound (but not fully so, just like flow) with the right flag(s). Here's the description of the "strict" compiler option that goes a long way to make your program more reliable : "Enable all strict type checking options. Enabling --strict enables --noImplicitAny, --noImplicitThis, --alwaysStrict and --strictNullChecks."
- tekacs 9y agoTypescript (even with all those options on) isn't even close to sound. Some of the soundness issues are by design (making directly overlayed JS code reasonable to type/interface with), some are due to 'taking too much time/design complexity if implemented'. I won't go into them one by one, but you can jump into most of the issues here to get a sense: https://github.com/Microsoft/TypeScript/issues?utf8=&q=Soundness https://github.com/Microsoft/TypeScript/issues?utf8=&q=Sound... https://github.com/Microsoft/TypeScript/issues?utf8=&q=unsound https://github.com/Microsoft/TypeScript/issues?utf8=&q=unsou... I won't take a position on the matter other than to say that it's a tricky balance and the TS team are at the very least extremely clear in saying that you should not be looking for a high degree of soundness here (JS interop is a higher priority). If those things are important, I would recommend Scala.js or PureScript or... anything more self contained (and remember that they're still ultimately dynamically typed on the JS boundary, just not inside the language). Here's the TS team explaining their position themselves: https://github.com/Microsoft/TypeScript/issues/9825#issuecomment-233843817 https://github.com/Microsoft/TypeScript/issues/9825#issuecom... https://github.com/Microsoft/TypeScript/issues/13003 https://github.com/Microsoft/TypeScript/issues/13003 (not the most cordial commenter unfortunately)