There should be a space between comment marker and comment

[f0i]

After a comment marker (//) at least one space should be inserted to improve readability.
Additional spaces should be preserved.

Examples:

• //some comment would be formatted as // some comment

// module {
//   asdf;
//}

would be formatted as

// module {          <- keep one space
//   asdf;           <- keep multiple spaces
// }                 <- add one space

[rvanasa]

Great suggestion! I'm currently trying to maintain consistency with the Prettier ecosystem (prettier/prettier#5755), although it seems totally reasonable to have this as an optional feature.