Fields can be declared to have a given type by using the %type
special field in a record descriptor. The synopsis is:
%type: field_list type_name_or_description
Where field_list is a list of field names separated by commas.
type_name_or_description can be either a type name which has
been previously declared using %typedef, or a type description.
Type names are useful when several fields are declared to be of the
same type:
%typedef: Id_t int %type: Id Id_t %type: Product Id_t
Anonymous types can be specified by writing a type description instead
of a type name. They help to avoid superfluous type declarations in
the common case where a type is used by just one field. A record
containing a single Id field, for example, can be defined
without having to use a %typedef in the following way:
%rec: Task %type: Id int