error

Function

  error — wrap a Zed value as an error

Synopsis

error(val: any) -> error

Description

The error function returns an error version of any value. It wraps the value val to turn it into an error type providing a means to create structured and stacked errors.

Examples

Wrap a record as a structured error:

echo '{foo:"foo"}' |
  super -z -c 'yield error({message:"bad value", value:this})' -

=>

error({message:"bad value",value:{foo:"foo"}})

Wrap any value as an error:

echo '1 "foo" [1,2,3]' | super -z -c 'yield error(this)' -

=>

error(1)
error("foo")
error([1,2,3])

Test if a value is an error and show its type "kind":

echo 'error("exception") "exception"' |
  super -Z -c 'yield {this,err:is_error(this),kind:kind(this)}' -

=>

{
    this: error("exception"),
    err: true,
    kind: "error"
}
{
    this: "exception",
    err: false,
    kind: "primitive"
}

Comparison of a missing error results in a missing error even if they are the same missing errors so as to not allow field comparisons of two missing fields to succeed:

echo '{}' | super -z -c 'badfield:=x |> yield badfield==error("missing")' -

=>

error("missing")