Implements the mapping concept. Constantly changing.
In map files, I use the term "constructor"; a constructor is implemented by a function.
TODO o ways to represent transport/derivation/paths o derivation o the biggest data structure - seems big and complex, especially split + free combination + solves type computation and transport attribution + other data structures are special cases o in between o view o visibility between two symbols o what about s ::= a | a a split? o "core" o the smallest data structure, just on path -> to small, the number is huge o String symbols in paths o nested definitions? o useful for terminals o library improvements o compose functions o function modifiers o dynamic function definition: o selection fields in awt example