A NamedTuple is typically created with a named tuple literal:

tuple = {name: "Crystal", year: 2011} # NamedTuple(name: String, year: Int32)
tuple[:name] # => "Crystal" (String)
tuple[:year] # => 2011      (Int32)

To denote a named tuple type you can write:

# The type denoting a named tuple of x: Int32, y: String
NamedTuple(x: Int32, y: String)

In type restrictions, generic type arguments and other places where a type is expected, you can use a shorter syntax, as explained in the type grammar:

# An array of named tuples of x: Int32, y: String
Array({x: Int32, y: String})

A named tuple key can also be a string literal:

{"this is a key": 1}

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