Struct TraceOp 

pub struct TraceOp {}

Implement trace! built-in.

It is equivalent to Idris or Haskell Trace, that is, it prints a message to stderr and pass a value along.

For instance

!(trace! "Here?" 42)

prints to stderr

Here?

and returns

[42]

Note that the first argument does not need to be a string, which makes trace! actually quite capable on its own. For instance

!(trace! ("Hello world!" (if True A B) 1 2 3) 42)

prints to stderr

(Hello world! A 1 2 3)

and returns

[42]

Trait Implementations

impl Clone for TraceOp

fn clone(&self) -> TraceOp

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl CustomExecute for TraceOp

fn execute(&self, args: &[Atom]) -> Result<Vec<Atom>, ExecError>

Executes grounded function on passed args and returns list of results as Vec<Atom> or [ExecError]. This is a restricted version of the [CustomExecute::execute_bindings] method which is implemented if returning of variable bindings is not required.

fn execute_bindings( &self, args: &[Atom], ) -> Result<Box<dyn Iterator<Item = (Atom, Option<Bindings>)>>, ExecError>

Executes grounded function on passed args and returns list of results with associated variable bindings if there are ones. Default implementation calls [CustomExecute::execute] and returns no bindings.

impl Debug for TraceOp

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

Formats the value using the given formatter.

impl Display for TraceOp

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

Formats the value using the given formatter.

impl Grounded for TraceOp

fn type_(&self) -> Atom

Returns type of the grounded atom. Should return same type each time it is called. [rust_type_atom] function can be used to implement default behavior if required.

fn as_execute(&self) -> Option<&dyn CustomExecute>

Returns reference to the custom execution API implementation. If None is returned then atom is not executable. See [CustomExecute] for details.

fn as_match(&self) -> Option<&dyn CustomMatch>

Returns reference to the custom matching API implementation. If None is returned then atom is matched by equality. See [CustomMatch] for details.

fn serialize(&self, _serializer: &mut dyn Serializer) -> Result<(), Error>

Implements serialization logic of the grounded atom. The logic is implemented in terms of the Rust native types. See [serial] for details.

impl PartialEq for TraceOp

fn eq(&self, _other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.