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Comment by aikah | Hacker News Reader

Here is the issue,at the end of the day,Typescript is just javascript with compile time type checking.Pattern matching would mean introducing "new" semantics which would make the compiled code much less readable than it is today.

Tomorrow if I want to drop Typescript,I can,because it still outputs readable javascript.Introduce something like pattern matching and it will not be an option anymore.

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I actually like cleanliness of Javascript generated from Typescript code. However I don't think that pattern matching would be more intrusive than, for example, module or class generation. Basically example from above could be compiled down to something like:

    var x = getResults();
    if(x instanceof Error) { ... }
    else if(x instanceof Results) { ... }

All the TypeScript examples use "instanceof". That's what a pattern matching block like this would compile down to, surely. And pattern matching on literals (eg., [x|xs]) would also translate to perfectly adequate JavaScript.

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