           numerator: numerator
           denominator: denominator
         )
-
     class_mixer _FromFractionObject
+
+    class _FromFnObject
+      initialize: (@converter, @fn_builder)->
+      isType: (js_object)->
+        js_object['fn'] instanceof Array
+      convert: (js_object)->
+        name = js_object['fn'][0]
+        argument = convert_implicit_subexp(js_object['fn'][1], @converter)
+
+        @fn_builder.build_fn(
+          name: name
+          argument: argument
+        )
+    class_mixer _FromFnObject
 
     class _FromStringLiteralObject
       initialize: (@converter, @literal_mappings)->

          @root_converter
          @variable_converter
          @fraction_converter
          ]

      process: (js_object)->

          @processor,
          @component_builder)

        @fn_converter = _FromFnObject.build(
          @processor,
          @component_builder
        )


        @string_literal_converter = _FromStringLiteralObject.build(@component_builder,{
          "+": "build_addition"
          "-": "build_subtraction"
