arktype•14mo ago

Best way to pass `Type` around

Hello! First, thanks for building this really cool library 🙏 I first heard of arktype while I was looking at the code of a framework called MUD, and while I was discussing CLI libraries with @frolic the other day, I thought that maybe it'd be a cool idea to have a CLI library that leverages arktype for arguments and options validation/parsing. I basically would like to have a function that receives args that are generated from arktype definitions. This is the code I have so far:

import { type Type, type, validateAmbient } from "arktype";
import { type ErrorMessage } from "@ark/util";

type ValidateArguments<T> = {
  [K in keyof T]: {
    type: validateAmbient<T[K]>;
  };
};

type ArkType = Type | Type<(_: any) => any>;

type InferredArkType<T> = T extends ArkType
  ? T["infer"]
  : ErrorMessage<"invalid Ark type">;

type ParseArguments<T> = {
  [K in keyof T]: InferredArkType<T[K]>;
};

type Command<T> = {
  arguments: ValidateArguments<T>;
  run(args: ParseArguments<T>): void | Promise<void>;
};

function defineCommand<const conf>(command: Command<conf>) {
  console.log(command);
}

defineCommand({
  arguments: {
    a: {
      type: type(`string>2`),
    },
    b: {
      type: type("string").narrow((address, ctx) => {
        if (address === [...address].reverse().join("")) {
          return true;
        }
        return ctx.mustBe("a palindrome");
      }),
    },
    c: {
      type: type(["string", "=>", parseFloat]),
    },
    d: {
      type: type("string.json").pipe.try(
        (s): object => JSON.parse(s),
        type({
          name: "string",
          version: "string.semver",
        })
      ),
    },
    f: {
      type: type("string|undefined"),
    },
  },
  run(args) {
    args.a;
    //   ^?
    args.b;
    //   ^?
    args.c;
    //   ^?
    args.d;
    //   ^?
    args.f;
    //   ^?
  },
});

import { type Type, type, validateAmbient } from "arktype";
import { type ErrorMessage } from "@ark/util";

type ValidateArguments<T> = {
  [K in keyof T]: {
    type: validateAmbient<T[K]>;
  };
};

type ArkType = Type | Type<(_: any) => any>;

type InferredArkType<T> = T extends ArkType
  ? T["infer"]
  : ErrorMessage<"invalid Ark type">;

type ParseArguments<T> = {
  [K in keyof T]: InferredArkType<T[K]>;
};

type Command<T> = {
  arguments: ValidateArguments<T>;
  run(args: ParseArguments<T>): void | Promise<void>;
};

function defineCommand<const conf>(command: Command<conf>) {
  console.log(command);
}

defineCommand({
  arguments: {
    a: {
      type: type(`string>2`),
    },
    b: {
      type: type("string").narrow((address, ctx) => {
        if (address === [...address].reverse().join("")) {
          return true;
        }
        return ctx.mustBe("a palindrome");
      }),
    },
    c: {
      type: type(["string", "=>", parseFloat]),
    },
    d: {
      type: type("string.json").pipe.try(
        (s): object => JSON.parse(s),
        type({
          name: "string",
          version: "string.semver",
        })
      ),
    },
    f: {
      type: type("string|undefined"),
    },
  },
  run(args) {
    args.a;
    //   ^?
    args.b;
    //   ^?
    args.c;
    //   ^?
    args.d;
    //   ^?
    args.f;
    //   ^?
  },
});

8 Replies

_roamin_OP•14mo ago

The first version of the ArkType type's definition was actually type ArkType = Type, but for some reason narrows and morphs weren't passing the check T extends Type, so I had to use type ArkType = Type | Type<(_: any) => any>; I guess my question is about what would be the best way to pass Type around and extract the out/infer type? I'm fairly new to arktype and I may not have made the best choice here 🙂

Dimava•14mo ago

Seems like you'd better use definitions

function defineCommand<const def>(
   o: {arguments: validateAmbient<def>
){
  type(o.arguments)
}
defineCommant({
  first: 'boolean',
   default: 'number = 123',
  json: 'string.json.parsed', 
  number: 'string.integer.parse',
  'optional?': 'string'
})

function defineCommand<const def>(
   o: {arguments: validateAmbient<def>
){
  type(o.arguments)
}
defineCommant({
  first: 'boolean',
   default: 'number = 123',
  json: 'string.json.parsed', 
  number: 'string.integer.parse',
  'optional?': 'string'
})

PIat•14mo ago

What does validateAmbient do?

Dimava•14mo ago

Scopeless validateDefinition (with one generic arg)

PIat•14mo ago

Nice and concise, thanks ☺️

_roamin_OP•14mo ago

Thanks! If I were to change your defineCommand definiton to the one below, how would you define args so that its props types all have the inferred types?

function defineCommand<const def>(o: {
  arguments: validateAmbient<def>;
  run: (args: ???<def>) => void;
}) { }

function defineCommand<const def>(o: {
  arguments: validateAmbient<def>;
  run: (args: ???<def>) => void;
}) { }

I tried using inferAmbient, but narrows/morphs don't get "fully" inferred:

function defineCommand<const def>(o: {
  arguments: validateAmbient<def>;
  run: (args: inferAmbient<def>) => void;
}) {}

defineCommand({
  arguments: {
    first: "boolean",
    default: "number = 123",
    number: ["string", "=>", parseFloat],
    "optional?": "string",
  },
  run(args) {
    args;
    // ^?
    // (parameter) args: {
    //   first: boolean;
    //   default: (In?: number | undefined) => Default<123>;
    //   number: (In: string) => Out<number>;
    //   optional?: string | undefined;
    // }
  },
});

function defineCommand<const def>(o: {
  arguments: validateAmbient<def>;
  run: (args: inferAmbient<def>) => void;
}) {}

defineCommand({
  arguments: {
    first: "boolean",
    default: "number = 123",
    number: ["string", "=>", parseFloat],
    "optional?": "string",
  },
  run(args) {
    args;
    // ^?
    // (parameter) args: {
    //   first: boolean;
    //   default: (In?: number | undefined) => Default<123>;
    //   number: (In: string) => Out<number>;
    //   optional?: string | undefined;
    // }
  },
});

Dimava•14mo ago

Type<inferAmbient<def>>.out or whatever the type()() return type is

_roamin_OP•14mo ago

I changed it to run: (args: Type<inferAmbient<def>>["infer"]) => void; and it's working perfectly! Thanks for your help 😉

Gaming

Programming

Best way to pass `Type` around

Did you find this page helpful?