E1026

E1026#

The patterns are complete so the usage of catch! is useless. In MoonBit, when there is only one error type that will be raised in a try block, compiler will know that the error type is the only one that will be caught. So, there is no need to use catch! in this case.

Erroneous example#

type! E

fn f() -> Unit!E {
  raise E
}

fn g() -> Unit! {
  try {
    f!()
  } catch! {
    E => raise E
  }
}

fn main {
  try {
    g!()
  } catch {
    _ => println("Error")
  }
}

Suggestion#

Remove the ! in the catch!:

type! E

fn f() -> Unit!E {
  raise E
}

fn g() -> Unit! {
  try {
    f!()
  } catch {
    E => raise E
  }
}

fn main {
  try {
    g!()
  } catch {
    _ => println("Error")
  }
}
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