According to the online specs, the lexer tries to tokenize by maximal matching (except for one exception in the case of ranges like "1..2"). The fact that this exception is stated seems to indicate that it's permitted to have two literals side-by-side without an intervening space.
So does that mean "1e2" should be tokenized as (float lit: 1e2) and "1f2" should be tokenized as (int lit: 1)(identifier: f2)? Or, for that matter, "123abcdefg" should be tokenized as (int lit: 123)(identifier: abcdefg) whereas "0x123abcdefg" should be tokenized as (int lit: 0x123abcdef)(identifier: g)? Or worse, if we still allow octals, "0129" should be tokenized as (octal lit: 012)(int lit: 9)? Or do we expect that any integer/float literal will always span the longest string that has characters permitted in any numerical literal, and then after the fact the lexer will give an error if the string cannot be interpreted as a legal literal? IOW, "0129" will first be scanned in its entirety as a numerical literal, then afterwards the lexer decides that '9' doesn't belong in an octal so it throws an error (as opposed to maximally matching "012" as an octal literal followed by a decimal literal "9"). Or, for that matter, "0123xel.u123" will be scanned as a numerical literal (since all the characters in it occur in some kind of numerical literal), and then an error generated after the fact when the lexer realizes that this string isn't a legal numerical literal? T -- All men are mortal. Socrates is mortal. Therefore all men are Socrates.