[munificent]

Almost all of the languages I know that do "flow typing" (TypeScript, Flow, Hack), "smart casts" (Kotlin), or "type promotion" (Dart) are fairly statement-oriented.

Expression-based languages tend to have pattern matching which provides another way to solve the same problem.

Flow typing is most useful in imperative languages where code like this is common:

    if (foo is! Bar) return "not a Bar";
    foo.someBarMethod();

Early returns and other imperative control flow is idiomatic and it's annoying if the static type system doesn't understand it.

In a more functional or expression-oriented language, early returns and other imperative control flow like that is rarer, so there's less "flowing" to type over.

[cannabis_sam]

How does pattern matching solve the same problem?

[munificent]

It gives you a very nice notation for checking if a value has some type and, if so, binding a new variable that refers to it as that more specific type.

[cannabis_sam]

How does that solve the problem of statements being devoid of return information?

Also, what? Pattern matching differentiate between values of a single type, and while the assignment mechanism is a great nice-to-have, it still completely follows the basic type consistency that actually typed functions provide.

Statements have none of these qualities..

[munificent]

I'm sorry, but we seem to be talking past each other.

Why is it a problem that statements are "devoid of return information"? A statement occurs in a position where, by definition, no value it produces will be used.