Credence.Pattern.NoEnumIntoEmptyMapset
(credence v0.7.0)
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Detects Enum.into/2 and Enum.into/3 targeting an empty MapSet.new()
and suggests MapSet.new/1 or MapSet.new/2 instead.
Why this matters
Enum.into(enum, MapSet.new()) and Enum.into(enum, MapSet.new(), fun) are
the generic collectable path for building MapSets. MapSet.new/1 and
MapSet.new/2 exist specifically for this purpose, are more readable, and
signal intent clearly.
LLMs frequently generate the Enum.into form because it is the
general-purpose collector they learn from many examples. An Elixir
developer would reach for MapSet.new by default.
Flagged patterns
| Pattern | Suggested replacement |
|---|---|
Enum.into(enum, MapSet.new()) | MapSet.new(enum) |
Enum.into(enum, MapSet.new(), fun) | MapSet.new(enum, fun) |
| `enum | > Enum.into(MapSet.new())` | MapSet.new(enum) |
| `enum | > Enum.into(MapSet.new(), fun)` | MapSet.new(enum, fun) |
Only the bare MapSet.new() call with no arguments is targeted.
Enum.into(enum, existing_mapset) where existing_mapset is not
MapSet.new() is left alone — it merges into an existing MapSet,
which MapSet.new does not do.