ASSIGN
assign to a global variable in state
Major Section: OTHER
Examples:
(assign x (expt 2 10))
(assign a (aset1 'ascii-map-array (@ a) 66 'Upper-case-B))
General Form:
(assign symbol term)
where symbol is any symbol (with certain enforced exclusions to
avoid overwriting ACL2 system ``globals'') and term is any ACL2
term that could be evaluated at the top-level. Assign evaluates
the term, stores the result as the value of the given symbol in the
global-table of state, and returns the result. (Note: the
actual implementation of the storage of this value is much more
efficient than this discussion of the logic might suggest.)
Assign is a macro that effectively expands to the more
complicated but understandable:
(pprogn (f-put-global 'symbol term state)
(mv nil (f-get-global 'symbol state) state)).
The macro @ gives convenient access to the value of such globals.
The :ubt operation has no effect on the global-table of state.
Thus, you may use these globals to hang onto useful data structures
even though you may undo back past where you computed and saved
them.