prefer-flat-map.md

Prefer _.flatMap over consecutive _.map and _.flatten

When using _.map and _.flatten, it can be more concise to use _.flatMap instead.

Rule Details

This rule takes no arguments.

Fail

_.map(f, a);

_.flatten(_.map(f, a));

_.flow(
  _.map(f1),
  _.flatten,
  f2
)

_.compose(
  f2,
  _.flatten,
  _.map(f1)
)

Pass

_.flatMap(f, a);

_.map(f, a);

_.flatten(a);

_.flow(
  _.flatMap(f1),
  f2
)

_.compose(
  f2,
  _.flatMap(f1)
)

_.flow(
  _.map(f1),
  f2,
  _.flatten
)

When Not To Use It

If you do not want to enforce using _.flatMap, and prefer _.map and _.flatten instead, you should not use this rule.