Type name with $ is invalid in F#

[Booksbaum]

There are several characters that aren't valid in F# type names (or module, namespace, union type case): .+$&[]/\*"'` . These are invalid even inside double-backticks. (BUT: are valid in other identifiers like variable name)

In TypeScript $ is allowed:

(simplified from @types/jest)

interface $JestEnvironment {
}

type Environment = $JestEnvironment;

=>

type [<AllowNullLiteral>] ``$JestEnvironment`` =
    interface end

type Environment =
    ``$JestEnvironment``

error FS0883: Invalid namespace, module, type or union case name

-> $ (and probably other invalid chars) should be removed in type names & co