SymbolThe symbol type:
symbol : U 0
Symbol literals are written using a sym` parsing directive and
a string lexeme. For example, sym`"foo".
The only operation on symbols is equality:
symbol_eqb : symbol -> symbol -> bool
istrue_symbol_eqb : forall (s t : symbol) . Bool.istrue (symbol_eqb s t) <-> s = t : symbol