std/named_tuple

struct ::NamedTuple(T)
  # Returns the value for *key*, or panics if missing.
  def [](key : Symbol)
  # Returns the value for string *key*, or panics if missing.
  def [](key : String)
  # Returns the value for *key*, or nil if missing.
  def []?(key : Symbol)
  def []?(key : String)
  # Deep clone of this named tuple, as far as the values allow: each value
  # whose type has `clone` is cloned and any other is kept as it is.
  # Asking every value for `clone` refused `{a: 1, b: "x"}`: the prelude
  # gives `clone` to neither `Int32` nor `String`, so only a named tuple of
  # values that all had one compiled.
  def clone
  # Yields each key symbol in order.
  def each_key(& : (Symbol -> Nil)) : Nil
  # Yields each key, value, and integer index.
  def each_with_index(offset : Int = 0) : Nil
  # Fetches value for *key*, returning *default_value* if missing.
  def fetch(key : Symbol, default_value)
  def fetch(key : String, default_value)
  # Fetches value for *key*, or yields to block if missing.
  def fetch(key : Symbol)
  def fetch(key : String)
  # Returns true if the named tuple has the given string key.
  def has_key?(key : String) : Bool
  # Merges another named tuple with self. Entries in *other* overwrite matching keys.
  def merge(other : NamedTuple)
  def merge(**other : **U) forall U
  # Creates a named tuple from keyword options.
  def self.new(**options : **T)
  # Merges self into other: self's values win on overlapping keys.
  def reverse_merge(other : NamedTuple)
  def reverse_merge(**other)
  # Converts this named tuple into an Array of {Symbol, Value} pairs.
  def to_a
  # Converts this named tuple into a Hash.
  def to_h
end