[damncabbage]

> It falls short on many things TS would immediately flag

I'm kind of curious what you've run into personally. Having a dependency without any type-defs get silently treated as `any` is my own beef, but I haven't hit much else yet.

(Some type-defs' use for `any` also gets my goat, such as Promise's catch argument and some of the lodash functions, but I'm considering that a separate thing.)

​

> And honestly, some of the decisions around the language just feel strange. Not knowing what kind of bool to use [0] is pretty emblematic of where it is going as a language.

This is more an existing JS weirdness (`true`/`false` vs `Boolean()`); Flow doesn't mess with runtime semantics, only adding a layer that you check with then strip out.

And TypeScript has the same thing:

  var a: boolean = new Boolean(1);
  
  // Produces:
  // NewTypering.ts(29,5): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.

[DanRosenwasser]

TypeScript's full error message on that last one is actually

  Type 'Boolean' is not assignable to type 'boolean'.
    'boolean' is a primitive, but 'Boolean' is a wrapper object. Prefer using 'boolean' when possible.

[WorldMaker]

«Having a dependency without any type-defs get silently treated as `any` is my own beef»

You can add the compiler flag --noImplicitAny to get errors if you prefer.