<c11:model xmlns:c11="http://www.cellml.org/cellml/1.1#" xmlns:c12="http://www.cellml.org/cellml/1.2#" xmlns:m="http://www.w3.org/1998/Math/MathML">
  <c11:component name="TypeLibrary">
    <!-- type_from_type_function_type: The type of a function which takes a type and returns a type. -->
    <c12:variable name="type_from_type_function_type" type="type" public_interface="yes" />
    <!-- cartesian_complex_type_function: A function which converts a scalar type (parameter)
           into the type of the cartesian form of the complex number as a vector of two reals
           having the type of the parameter. -->
    <c12:variable name="complex_type_function" type="type_from_type_function_type" public_interface="yes"/>

    <!-- The following variables are used locally for bvars and the like only... -->
    <c12:variable name="base_type" type="type" />

    <m:math>
      <!-- type_from_type_function = function_type(type, type) -->
      <m:apply id="type_from_type_function_eqn"><m:eq/>
        <m:ci>type_from_type_function</m:ci>
        <m:apply><c12:function_type />
          <m:ci>type</m:ci>
          <m:ci>type</m:ci>
        </m:apply>
      </m:apply>

      <!-- We might want to build this into CellML 1.2 core (with the option
           that secondary specification don't support it) but if not, this is
           how complex numbers in their cartesian form could be defined. We
           probably should 
        -->
      <m:apply id="cartesian_complex_type_function_eqn"><m:eq/>
        <!-- complex_type_function = lambda base_type: vector_type(base_type, 2) -->
        <m:ci>complex_type_function</m:ci>
        <m:lambda>
          <m:bvar><m:ci>base_type</m:ci></m:bvar>
        </m:lambda>
        <m:apply><c12:vector_type />
          <!-- First argument: type of vector elements... -->
          <m:ci>base_type</m:ci>
          <!-- Second argument: size of vector -->
          <m:cn c12:type="real_dimensionless">2</m:cn>
        </m:apply>
      </m:apply>
    </m:math>
  </c11:component>
</c11:model>