Backtracking control -- tokens

"182745909809283949 minus 4" ~~ / \d+: ' plus ' \d+: /

For modern one-pass languages, non-backtracking regexes are very common

The keyword "token" indicates a regex that does no backtracking by default

"182745909809283949 minus 4" ~~ token { \d+ ' plus ' \d+ }

Examples:

token integer  { \d+ }

token ident    { <alpha> \w* }

token variable { [ '$' | '@' | '%' ] <ident> }