arktype•3w ago

Redundant match default

Match has a default case But it is something completely different from .default, which makes sense However, it can lead to writing the same code 2 times. In particular, this can be seen in the Fluent API:

const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none)
  .default(() => none)

const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none)
  .default(() => none)

Is there a build-in way to do this? E.g.

const sortDirectionMatch = match({
  '"DESC"': () => desc,
  '"ASC"': () => asc,
  'default?': () => none,
})
// or
const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none, true)

const sortDirectionMatch = match({
  '"DESC"': () => desc,
  '"ASC"': () => asc,
  'default?': () => none,
})
// or
const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none, true)

Or is it best to just make a wrapper that adds these 2 versions like (untyped):

function optionalMatch(matchDraft, defaultCb) {
  return matchDraft
    .default(defaultCb)
    .default(defaultCb);
}

function optionalMatch(matchDraft, defaultCb) {
  return matchDraft
    .default(defaultCb)
    .default(defaultCb);
}

4 Replies

TizzySaurus•3w ago

I don't understand your point here... what's the runtime difference between

const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none)

const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none)

and

const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none)
  .default(() => none)

const sortDirectionMatch = match
  .case('"DESC"', () => desc)
  .case('"ASC"', () => asc)
  .default(() => none)
  .default(() => none)

UntlsnOP•3w ago

Right I should point out that it mainly matters when using match in an object Second one make property optional just like .default with other types When first one still require it, just use it as fallback when given value don't fit

TizzySaurus•3w ago

Right... would making the object keys all optional fix it?

UntlsnOP•3w ago

Not quite Making key optional make it just optional So in case above instead of none we will get just undefined

Gaming

Programming

Redundant match default

Did you find this page helpful?