Types
These are special functions that may be used in declaring the allowed values for a variable, eg:
Types can also be called just like other functions.
See Using Types.
type struct_index(integer idx) return idx>=1 and idx<=length(struct_defs) end typeA type must have exactly one parameter and should return an atom that is either true (non-zero) or false (zero).
Types can also be called just like other functions.
See Using Types.