he/him 
After using TypeScript there's some features that I'm terrified of that seem counter intuitive. All the following examples produce NO errors and are with every single strict TS option enabled.
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Type predicates are just an annotation and aren't actually checked. Meaning you can do some pretty wacky and unsafe things. Is there an technical constraint preventing TS from checking these?pic.twitter.com/qtIIzM1Cat
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As expressions are another one. The safety guarantees are minuscule. I find the overlapping semantics to be confusing and not actually useful.pic.twitter.com/SqqnJxRz5H
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Refining 'unknown' to an array produces 'Array<any>' where as 'Array<unknown>` would make more sense. Not sure if it does in other places too.pic.twitter.com/gsRa67JFFk
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When you use as, you are telling the system that you're narrowing it yourself. It will only warn if the narrowing doesn't make sense.
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It's doing some checking though, I just don't understand the semantics. I would understand it's existence of TS had proper type casts, like in Flow, but I can't find anything like it.
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I think of `as` as an escape hatch that should be avoided unless there is no other option
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I just always call them 'typecasts', since that's what they are?
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I try and treat "as" the same as casting through a void* pointer in cpp. I wish there was a "disable using 'as' to widen types" options. Narrowing makes sense sometimes but widening is scary
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You can treat all 'as' statements as you overruling the compiler, so you're on your own from there. It'll only stop you if it can prove you're 100% wrong. You should be able to mostly avoid them, since cases where the compiler needs overriding *should* be rare.
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