Prettier formats a sensible one-liner into seven lines

Prettier 1.15.3 Playground link

--parser babylon

Input:

eventStore.update(id, _.flow(updater, incrementVersion))

Output:

eventStore.update(
  id,
  _.flow(
    updater,
    incrementVersion
  )
);

Expected behavior: Unchanged:

eventStore.update(id, _.flow(updater, incrementVersion))

[duailibe]

I think we maybe should revisit this heuristic.

[sam3d]

Could such a function call default to being one-line (as long as it’s within the character limit), but in the same way that an object can always be made to be on multiple lines if a newline is added after {, this could this be made to adapt the following behaviour:

• If the function call has at least one argument that is also a function call
• and a newline is present immediately after the first opening parentheses of the first function call
• then split the function over multiple lines

OR

• If the function call has at least one argument that is also a function call
• and part of the function is split over multiple lines already
• but no newline is present after the first opening parentheses
• then collapse the partially multiline function down to one line
• only if the resulting function call length does not exceed the character limit

This would also have the benefit of not affecting existing prettier code that has already been split over multiple lines by the existing heuristic.

It also brings it much more in-line with the way that prettier handles objects over multiple lines.

It also doesn’t rely on special function name detection, and as it is specific enough to only apply to function calls within function calls, it can handle many of these edge-cases without either being too constrictive or too open.

---

Just the one-liner as is

Input:

eventStore.update(id, _.flow(updater, incrementVersion))

Output:

eventStore.update(id, _.flow(updater, incrementVersion));

---

A newline after the first opening parentheses of the first function call

Input:

eventStore.update(
id, _.flow(updater, incrementVersion))

Output:

eventStore.update(
  id,
  _.flow(
    updater,
    incrementVersion
  )
);

---

Multiple lines, but no newline between first opening parentheses of first function call and first parameter

Input:

eventStore.update(id,
  _.flow(
    updater,
    incrementVersion
  )
);

Output:

eventStore.update(id, _.flow(updater, incrementVersion));

---

A one-liner with a parameter function call that exceeds the character limit

Input:

eventStore.update(id, _.flow(updater, incrementVersion), aReallyLongArgumentThatGoesPast80Characters)

Output:

eventStore.update(
  id,
  _.flow(
    updater,
    incrementVersion
  ),
  aReallyLongArgumentThatGoesPast80Characters
);