Identity Monad - Take a value and give the value back with bind.

identity_monad.js

function MONAD() {
  return function unit(value) {
    var monad = Object.create(null);
    monad.bind = function(func) {
      return func(value);
    };
    return monad;
  };
}

=== Axioms ===
--function way--

bind(bind(monad, f), g)
monad.bind(f).bind(g)

--method way--

unit(value).bind(f) ==== f(value
monad.bind(unit) ==== monad
monad.bind(f).bind(g) ==== monad.bind(function(value) {
  return f(value).bind(g);
};
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