Module traits 

Builtin trait system: Builtin, FromArgs, CoerceArg, and argument decoding helpers.

R arguments have three states that matter: missing (not provided), NULL (explicitly passed), or a value. This module models all three through the RArg<T> enum and provides derive-friendly coercion traits.

Structs

BuiltinInfo

Metadata for a trait-based builtin, generated by #[derive(FromArgs)].

Dots

Captures all remaining positional arguments (... in R).

Enums

RArg

The three states of an R function argument.

Traits

Builtin

A trait-based builtin function.

CoerceArg

Coerce an RValue to a Rust type. Implemented for common R parameter types.

FromArgs

Decode R call arguments into a typed struct.

Functions

coerce_arg

Helper called by FromArgs derive-generated code.

coerce_arg_three_way

Helper called by FromArgs derive-generated code for RArg<T> fields. Produces the three-way Missing/Null/Value from a raw Option<&RValue>.

find_arg

Find an argument by name (with partial matching) or positional index.

find_named_arg

Find an argument by name only (exact match first, then unique partial match). Used by the FromArgs derive macro with a runtime positional counter.