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1. Pattern Matching Pattern matching has been by far my most favorite feature as someone coming from TypeScript: https://gist.github.com/peterpme/10840585ddced

1. Pattern Matching Pattern matching has been by far my most favorite feature as someone coming from TypeScript: https://gist.github.com/peterpme/10840585ddced15a7f4ecd05394e6091 https://gist.github.com/peterpme/10840585ddced15a7f4ecd05394... The ability to use "constants" that are inherently typed mean less mistakes and a better path forward for handling your application state. Refactoring with this in mind, becomes a lot safer. For example, if I had a reducer that needed a new action, I would add that action to the `type`. The compiler would then tell me every place I needed to handle that case. 2."Implicit" Types (types that don't get in the way) I don't need to type everything like I would in TypeScript. ReasonML already figures all of that out for me. I _can_ add the type if I want (for readability purposes). There is no such thing a `any` or any type of escape hatch for that (this can be frustrating at first) but once you get it, you write code more confidently. 3. React & Refactoring Say I've got a bunch of React components I need to refactor. Reason types both the prop key and value. If I remove a prop or change that prop's data structure, I'll immediately know all the places I need to make that change. I know some folks may roll their eyes when they read this, but after using both Reason and TypeScript at Draftbit, I strongly believe it's a competitive advantage. The stuff we ship in Reason just doesn't break.

machiaweliczny 6y ago
Is it possible to compile in presence of errors? I love TS that it's gradual and for prototyping I can use "transpileOnly" and after I'm done I can verify everything. I have bad memories from typing json interfeces for Elm while prototyping (maybe could be disabled).
- pkilgore 6y ago
  No, but you can slowly Reason-ify a javascript (or typescript!) app at the interfaces using gentype[1], which emits javascript/typescript/flow interfaces for the reason side. It works perfectly well to ship a slowly-becoming-reason frontend app. But you do have to have the compiler give the thumbs up before it will compile the reason side of the project. You can also checkout the tutorial for slowly converting a single file here, although I find myself doing this sort of thing very rarely: https://reasonml.github.io/docs/en/converting-from-js https://reasonml.github.io/docs/en/converting-from-js [1] https://github.com/cristianoc/genType https://github.com/cristianoc/genType

machiaweliczny 6y ago

Is it possible to compile in presence of errors? I love TS that it's gradual and for prototyping I can use "transpileOnly" and after I'm done I can verify everything. I have bad memories from typing json interfeces for Elm while prototyping (maybe could be disabled).

pkilgore 6y ago
No, but you can slowly Reason-ify a javascript (or typescript!) app at the interfaces using gentype[1], which emits javascript/typescript/flow interfaces for the reason side. It works perfectly well to ship a slowly-becoming-reason frontend app. But you do have to have the compiler give the thumbs up before it will compile the reason side of the project. You can also checkout the tutorial for slowly converting a single file here, although I find myself doing this sort of thing very rarely: https://reasonml.github.io/docs/en/converting-from-js https://reasonml.github.io/docs/en/converting-from-js [1] https://github.com/cristianoc/genType https://github.com/cristianoc/genType