# elm-review-positional-arguments

Provides an [`elm-review`](https://package.elm-lang.org/packages/jfmengels/elm-review/latest/) rule to limit the number of positional arguments to functions.

## Provided rule

- [`NoTooManyPositionalArguments`](https://package.elm-lang.org/packages/cekrem/elm-review-positional-arguments/1.0.0/NoTooManyPositionalArguments) - Reports functions that have too many positional arguments and can auto-fix them to use a record parameter instead.

## Configuration

```elm
module ReviewConfig exposing (config)

import NoTooManyPositionalArguments
import Review.Rule exposing (Rule)

config : List Rule
config =
    [ NoTooManyPositionalArguments.rule NoTooManyPositionalArguments.defaults
    ]
```

The default maximum is 4 positional arguments. Functions with 5 or more will be flagged.

## What it does

When a function has too many positional arguments, the rule reports an error and provides an automatic fix that:

1. Converts the function declaration to accept a single record with named fields
2. Updates the type annotation (if present) to use a record type
3. Updates all call sites within the same module to pass a record

### Before

```elm
createUser : String -> String -> Int -> Bool -> String -> User
createUser name email age isAdmin role =
    { name = name, email = email, age = age, isAdmin = isAdmin, role = role }

register =
    createUser "Alice" "alice@example.com" 30 False "admin"
```

### After

```elm
createUser : { name : String, email : String, age : Int, isAdmin : Bool, role : String } -> User
createUser { name, email, age, isAdmin, role } =
    { name = name, email = email, age = age, isAdmin = isAdmin, role = role }

register =
    createUser { name = "Alice", email = "alice@example.com", age = 30, isAdmin = False, role = "admin" }
```

## When the fix is suppressed

The auto-fix is intentionally suppressed when:

- **Partial application is detected** -- converting to a record would break curried usage like `List.map (createUser "default")`.
- **Parameters use destructuring patterns** -- e.g. `foo (Just x) (Ok y) _ _ _` has no usable names for record fields.

In these cases, the error is still reported but must be fixed manually.

## Try it out

You can try the example configuration above out by running the following command:

```bash
elm-review --template cekrem/elm-review-positional-arguments/example
```