How can I express syntax rules like "[0-9/.:*+!_'?-]
are valid symbol constituent, but not as the first char"?
Or "/
is a valid symbol constituent, but can only appear once and in the middle of a symbol".
How can I express syntax rules like "[0-9/.:*+!_'?-]
are valid symbol constituent, but not as the first char"?
Or "/
is a valid symbol constituent, but can only appear once and in the middle of a symbol".