Module: Kwurry

Included in:
Proc
Defined in:
lib/kwurry.rb,
lib/kwurry/version.rb

Constant Summary collapse

VERSION = 
"0.2.0"

Instance Method Summary collapse

Instance Method Details

#kwurry ⇒ Object 



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# File 'lib/kwurry.rb', line 4

def kwurry
  # index keyword names by keyword type
  ki = parameters.reduce(Hash.new { |h, k| h[k] = [] }) { |h, (type, name)| h[type] << name; h }
  keyreqs = ki[:keyreq]
  keyopts = ki[:key]
  keyrest = ki[:keyrest].any?

  # accepts keyword names of all passed arguments
  # raises error if invalid keyword names supplied
  # returns true if all required keyword names supplied
  # returns false otherwise (indicates partially-applied lambda should be returned)
  apply = ->(keys) {
    if !keyrest
      invalid_keys = (keys - (keyreqs + keyopts))
      raise ArgumentError.new("unknown keyword: #{invalid_keys}") if invalid_keys.any?
    end
    (keyreqs - keys).empty?
  }

  # accepts any previously passed kwargs
  # returns a lambda that accepts any kwargs which ...
  # * returns result of original lambda if should apply
  # * otherwise invokes factory to return partially-applied curried lambda
  factory = ->(**applied_kwargs) {
    ->(**kw) {
      kwargs = applied_kwargs.merge(kw)
      return self.(**kwargs) if apply.(kwargs.keys)
      factory.(**kwargs)
    }
  }

  # factory and apply are defined in this closure so they can access
  # keyreqs, keyopts, keyrest
  # as well as self (original lambda) to eventually invoke it

  # inovke factory (with no args) to curry the lambda initially
  # return the curried lambda it returns
  factory.()
end