Enum KernelError 

#[non_exhaustive]
pub enum KernelError {
    Parse {
        errors: Vec<ParseError>,
        message: String,
    },
    Validation {
        issues: Vec<ValidationIssue>,
        message: String,
    },
    Execution(Error),
}

Why a call to crate::kernel::Kernel::execute (or a sibling — execute_with_options, execute_argv, …) did not return a result.

The essential distinction is rejected before running versus failed while running. KernelError::is_rejected answers that question without inspecting Display text; match on the variant for the finer detail each rejection carries (issue codes, spans, parse locations).

• KernelError::Parse and KernelError::Validation are rejections: the kernel never ran a statement.
• KernelError::Execution means a statement started running and something failed partway through — a builtin, the evaluator, an IO fault, or any other error the interpreter propagated.

Display on every variant reproduces exactly what Kernel::execute returned before this type existed, so a caller that only prints the error sees no change on upgrade.

#[non_exhaustive]: a rejection reason can be added later — a refused external command is one candidate under discussion — without breaking a caller that already has a wildcard arm. Add a match arm rather than expect this list to stay closed.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Parse

The input did not lex or parse. Nothing ran.

Fields

errors: Vec<ParseError>

Every lex/parse failure found, in source order. Each carries its own span; errors[i].format(source) reproduces one line of message.

message: String

Pre-rendered "parse error:\n..." text, byte-identical to what Kernel::execute returned as an anyhow::Error before this type existed.

Validation

The pre-execution validator rejected the program. Nothing ran.

Fields

issues: Vec<ValidationIssue>

Every error-severity issue the validator raised, carrying its kaish_tool_api::IssueCode, message, and span. Warnings never appear here — they don’t prevent execution, so they surface on the successful ExecResult instead.

message: String

Pre-rendered "validation failed:\n..." text, byte-identical to what Kernel::execute returned as an anyhow::Error before this type existed.

Execution(Error)

A statement started running and something failed partway through — a builtin, the evaluator, dispatch, or an IO fault. Carries the original error chain unchanged; source() and {:#} still walk it.

Implementations

impl KernelError

pub fn is_rejected(&self) -> bool

The program was rejected before anything ran — a lex/parse failure (KernelError::Parse) or a validator rejection (KernelError::Validation). No statement executed, so nothing an embedder retries would have a different partial side effect.

pub fn is_execution_failure(&self) -> bool

A statement began running and faulted partway through (KernelError::Execution). The complement of Self::is_rejected.

Trait Implementations

impl Debug for KernelError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for KernelError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for KernelError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.