gRPC: kavach proto

● Intermediate2 min

kavach proto writes the .proto file for your types, so a service in any other language can generate matching code.

type Status = Pending | Paid(amount: Float)

type Order {
    id: Int
    item: String
    qty: Int = 1
    status: Status
    tags: [String]
    notes: [String: String]
}

fn main() {
}

terminal

kavach proto src/main.kav

// Written by `kavach proto` from src/main.kav.
syntax = "proto3";

message Status {
  oneof value {
    Pending pending = 1;
    Paid paid = 2;
  }
  message Pending {}
  message Paid {
    double amount = 1;
  }
}

message Order {
  int64 id = 1;
  string item = 2;
  int64 qty = 3;
  Status status = 4;
  repeated string tags = 5;
  map<string, string> notes = 6;
}

A union becomes a message with a oneof; a list is repeated; a map with text keys is a map.
Add new fields at the end of a record: older clients keep working. Reordering fields breaks them.