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".