[Question] Generic support for trait

[yamajik]

Any possible to introduce Rust From/Into into Moonbit?

Currently, I'm working on a native project, which needs to bind structs between Moonbit/Rust. Built-in From/Into traits in Rust are an elegant way for conversion, I am looking for the very same way in Moonbit. Here's my proposal.

enum Type {
  TypeA
  TypeB(Int)
  TypeC(field1~: Int, field2~: Int)
}

struct CTypeStruct {
  tag: TypeTag
  data: TypeData
}

enum TypeTag {
  TypeA = 0
  TypeB = 1
  TypeC = 2
}

struct TypeData {
  b: Option[TypeBData]
  c: Option[TypeCData]
}

struct TypeBData {
  val: Int
}

struct TypeCData {
  field1: Int
  field2: Int
}

impl From[CTypeStruct] for Type with from {
  fn from(value: CTypeStruct) -> Self {
    match value.tag {
      TypeTag::TypeA => Type::TypeA
      TypeTag::TypeB => Type::TypeB(value.data.b.unwrap().val)
      TypeTag::TypeC => {
        let { field1, field2 } = value.data.c.unwrap();
        Type::TypeC(field1=field1, field2=field2)
      }
    }
  }
}

impl From[Type] for CTypeStruct with from {
  fn from(value: Type) -> Self {
    match value {
      Type::TypeA => {
        tag: TypeTag::TypeA,
        data: TypeData::empty(),
      }
      Type::TypeB(val) => {
        tag: TypeTag::TypeB,
        data: { b: Some({ val }), c: None },
      },
      Type::TypeC { field1, field2 } => {
        tag: TypeTag::TypeC,
        data: { b: None, c: Some(TypeCData { field1, field2 }) },
      },
    }
  }
}

[peter-jerry-ye]

We are not adding trait with parameters in the near future. We want to keep the language simple without introducing features that would slow down or complicate the compiler.

Closing as it is tracked here: moonbitlang/moonbit-evolution#5