WELL_FORMED_FUNCTOR_PATTERN
The pattern of a well-formed functor for a Struct. A functor is well-formed if and only if:
it starts with a lower-case letter
it only contains letters, digits, or underscores
The pattern of a well-formed functor for a Struct. A functor is well-formed if and only if:
it starts with a lower-case letter
it only contains letters, digits, or underscores