@nikitonsky I was about to reply that none of those changes break the reader in unusual way when older version of clojure is used. like reader of any version of clojure prior to 1.10 will not read ##Inf as something valid, exception will be thrown. Unlike 42_000 that can be read as 42 followed by a symbol _000.

But I forgot that underscore does not stop number reading in any version of clojure. So I don't know any technical difficulties in adding separators for number literals.