Checking for non-empty values

[viveleroi]

What's the recommended way to ensure a value is a string and not empty:

I'm matching an object with structure { text: string } but I need to ensure the text string is also not empty. If it's empty, I still want the otherwise method to trigger.

const text = match(value)
    .with({ text: P.string }, selected => selected.text)
    .otherwise(() => placeholder)

So far, it seems like this is what I need to do, I don't see any shorter ways:

function isNonEmptyString(value: unknown): value is string {
  return typeof value === 'string' && value !== ''
}

const text = match(value)
  .with(
    {
      text: P.when(isNonEmptyString)
    },
    selected => selected.text
  )
  .otherwise(() => placeholder)

[gvergnaud]

Sorry for the late reply, but with TS-Pattern v5, you can now use P.string.minLength(1)!

const text = match(value)
  .with(
    { text: P.string.minLength(1) },
    selected => selected.text
  )
  .otherwise(() => placeholder)