Comment by posix_monad

MLs require a lot of ceremony modelling simple record types.

What we want to express here is an object with a map of properties (name to type):

    string Type map

For the OOP minded:

    Map<string, Type>

And also compose those:

    type Foo = { "_foo", int }

    type Bar = { "_bar", string }

    type FooBar = mergeMaps Foo Bar

But at compile-time, of course.

Have any languages achieved this? I know TypeScript can do some of these things, but it's clunky.