# ExSlop
[](https://hex.pm/packages/ex_slop)
Credo checks that catch AI-generated code slop in Elixir.
18 checks for patterns that LLMs produce but experienced Elixir developers
don't — blanket rescues, narrator docs, obvious comments, anti-idiomatic
Enum usage, try/rescue around non-raising functions, N+1 queries, and more.
None of these overlap with built-in Credo: Credo never inspects doc/comment
**content**, doesn't catch Ecto anti-patterns or identity passthrough, and its
`MapInto` / `CaseTrivialMatches` checks are disabled or deprecated.
## Installation
Add to `mix.exs`:
```elixir
def deps do
[
{:ex_slop, "~> 0.1", only: [:dev, :test], runtime: false}
]
end
```
Then add the checks you want to your `.credo.exs` — just append to the
existing `enabled` list:
```elixir
# .credo.exs
{ExSlop.Check.Warning.BlanketRescue, []},
{ExSlop.Check.Warning.RescueWithoutReraise, []},
{ExSlop.Check.Warning.RepoAllThenFilter, []},
{ExSlop.Check.Warning.QueryInEnumMap, []},
{ExSlop.Check.Warning.GenserverAsKvStore, []},
{ExSlop.Check.Refactor.FilterNil, []},
{ExSlop.Check.Refactor.ReduceAsMap, []},
{ExSlop.Check.Refactor.MapIntoLiteral, []},
{ExSlop.Check.Refactor.IdentityPassthrough, []},
{ExSlop.Check.Refactor.IdentityMap, []},
{ExSlop.Check.Refactor.CaseTrueFalse, []},
{ExSlop.Check.Refactor.TryRescueWithSafeAlternative, []},
{ExSlop.Check.Refactor.WithIdentityElse, []},
{ExSlop.Check.Readability.NarratorDoc, []},
{ExSlop.Check.Readability.DocFalseOnPublicFunction, []},
{ExSlop.Check.Readability.BoilerplateDocParams, []},
{ExSlop.Check.Readability.ObviousComment, []},
{ExSlop.Check.Readability.StepComment, []}
```
Cherry-pick only the checks that make sense for your project.
## Checks
### Warnings
| Check | What it catches |
|-------|-----------------|
| `BlanketRescue` | `rescue _ -> nil` or `rescue _e -> {:error, "..."}` |
| `RescueWithoutReraise` | `rescue e -> Logger.error(...); :error` — logs but swallows |
| `RepoAllThenFilter` | `Repo.all(User) \|> Enum.filter(& &1.active)` — filter in SQL |
| `QueryInEnumMap` | `Enum.map(users, fn u -> Repo.get(...) end)` — N+1 query |
| `GenserverAsKvStore` | GenServer that's just `Map.get`/`Map.put` on state — use ETS or Agent |
### Refactoring
| Check | Bad | Good |
|-------|-----|------|
| `FilterNil` | `Enum.filter(fn x -> x != nil end)` | `Enum.reject(&is_nil/1)` |
| `ReduceAsMap` | `Enum.reduce([], fn x, acc -> [f(x) \| acc] end)` | `Enum.map(&f/1)` |
| `MapIntoLiteral` | `Enum.map(...) \|> Enum.into(%{})` | `Map.new(...)` |
| `IdentityPassthrough` | `case r do {:ok, v} -> {:ok, v}; {:error, e} -> {:error, e} end` | `r` |
| `IdentityMap` | `Enum.map(fn x -> x end)` | remove the call |
| `CaseTrueFalse` | `case flag do true -> a; false -> b end` | `if flag, do: a, else: b` |
| `TryRescueWithSafeAlternative` | `try do String.to_integer(x) rescue _ -> nil end` | `Integer.parse(x)` |
| `WithIdentityElse` | `with {:ok, v} <- f() do v else {:error, r} -> {:error, r} end` | drop the `else` |
### Readability
| Check | What it catches |
|-------|-----------------|
| `NarratorDoc` | `@moduledoc "This module provides functionality for..."` |
| `DocFalseOnPublicFunction` | `@doc false` on `def` — document it or make it `defp` |
| `BoilerplateDocParams` | `## Parameters\n- conn: The connection struct` |
| `ObviousComment` | `# Fetch the user` above `Repo.get(User, id)` |
| `StepComment` | `# Step 1: Validate input` |
## License
[MIT](LICENSE)
