(get signal) ↦ (int?) name : string?
(slice signal upper lower) ↦ (int?) signal : symbol? upper : int? lower : int?
(reval expr offset) ↦ (int?) expr : WAL expression offset : int?
expr@off ↦ (reval expr offset) expr : WAL expression offset : int?
>-> INDEX 5 >-> (reval INDEX -1) 4 >-> INDEX@-1 4 >-> INDEX@(+ 2 2) 9
expr@<off-1 off-2 ... off-n> ↦ expr@off-1 expr@off-2 ... expr@off-n expr : WAL expression off-i : int?
(print top.valid@<1 2 3>) expands to (print top.valid@1 top.valid@2 top.valid@3)