package wasi:io@0.2.1;

@since(version = 0.2.0)
interface error {
    /// A resource which represents some error information.
    ///
    /// The only method provided by this resource is `to-debug-string`,
    /// which provides some human-readable information about the error.
    ///
    /// In the `wasi:io` package, this resource is returned through the
    /// `wasi:io/streams/stream-error` type.
    ///
    /// To provide more specific error information, other interfaces may
    /// offer functions to "downcast" this error into more specific types. For example,
    /// errors returned from streams derived from filesystem types can be described using
    /// the filesystem's own error-code type. This is done using the function
    /// `wasi:filesystem/types/filesystem-error-code`, which takes a `borrow<error>`
    /// parameter and returns an `option<wasi:filesystem/types/error-code>`.
    ///
    /// The set of functions which can "downcast" an `error` into a more
    /// concrete type is open.
    @since(version = 0.2.0)
    resource error {
        /// Returns a string that is suitable to assist humans in debugging
        /// this error.
        ///
        /// WARNING: The returned string should not be consumed mechanically!
        /// It may change across platforms, hosts, or other implementation
        /// details. Parsing this string is a major platform-compatibility
        /// hazard.
        @since(version = 0.2.0)
        to-debug-string: func() -> string;
    }
}