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Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

exactly 🙂

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

ah gotcha. or for e.g. number, once you use subtypes such as number > 0, you are opting out of the compile time check, but for simple cases with simple types and no subtypes it could work

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

I dunno if that is a confusing DX though

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

I'm suggesting an explicitly not sound compile-time check, such that it compiling may not mean it is exhaustive at runtime, but it being not exhaustive at compile time definitely means it is obviously wrong

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

if it would be possible to add simple compile-time checks for exhaustiveness backed up by a runtime check, that would be amazing. (the compile time checks wouldn't be complete, but if they catch the obvious stuff, that would be helpful for development rather than needing you to run the code to see you have an obvious match case missing, e.g. for the simple discriminated union case)

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

thank you!

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

yeah, it unfortunately gets complicated with type expressions like that ... I am mostly only using it for matching on a discriminated union type, where exhaustiveness checking is easy

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

e.g.

const discriminateValue = match
  // .in allows you to specify the input TypeScript allows for your matcher
  .in<Data>()
  .out<string>() // <-- something like this
  // .at allows you to specify a key at which your input will be matched
  .at("id")
  .match({
    "'one'": (o) => `${o.oneValue}!`,
    "'two'": (o) => o.twoValue,
    default: "assert",
  });

const discriminateValue = match
  // .in allows you to specify the input TypeScript allows for your matcher
  .in<Data>()
  .out<string>() // <-- something like this
  // .at allows you to specify a key at which your input will be matched
  .at("id")
  .match({
    "'one'": (o) => `${o.oneValue}!`,
    "'two'": (o) => o.twoValue,
    default: "assert",
  });

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

another matching question: is there something similar to Effect's Match.withReturnType<T>() that allows me to constrain in an arktype Match the allowable return values for pattern expressions?

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

Effect's match has that "block of string literals" utility, btw, not sure if you have seen:

      Match.when(
        Match.is("keyOne", "keyTwo"),
        () => "case_one_val",
      ),
      Match.when(
        "keyThree",
        () => "case_two_val",
      ),

      Match.when(
        Match.is("keyOne", "keyTwo"),
        () => "case_one_val",
      ),
      Match.when(
        "keyThree",
        () => "case_two_val",
      ),

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

follow-up unrelated question: is there something similar to effect's Match.exhaustive that I can use to assert that the matcher is exhaustive?

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

haha, I just realized that myself. It's been a while since I wrote arktypes, have been extremely deep in the Effect ecosystem for a while because that's what we use for all of our services and dependency management

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

yep!@

57 replies

Aarktype

•Created by francis on 3/1/2025 in #questions

New v2.1 arktype matcher: is there a way to match on string literal values?

figured it out

57 replies

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