Struct WitnessRef 

pub struct WitnessRef<'a, T> { /* private fields */ }

A node of a Witness: its constructor, its type, and its fields.

Examples

let arms = [Arm::new(Pat::product([Pat::wild(), Pat::bool(true)]))];
let report = check(&Pair, &true, &arms)?;
let root = report.missing()[0].root();
assert_eq!(root.ctor(), Ctor::Product);
assert_eq!(root.arity(), 2);
let second = root.fields().nth(1).unwrap();
assert_eq!((second.ctor(), *second.ty()), (Ctor::Bool(false), false));

Implementations

impl<'a, T> WitnessRef<'a, T>

pub fn ctor(&self) -> Ctor

The constructor at this node.

Examples

let report = check(&Flag, &(), &[Arm::new(Pat::bool(true))])?;
assert_eq!(report.missing()[0].root().ctor(), Ctor::Bool(false));

pub fn ty(&self) -> &'a T

The type of the value at this node.

Examples

let report = check(&Flag, &7, &[])?;
assert_eq!(*report.missing()[0].root().ty(), 7);

pub fn arity(&self) -> usize

The number of fields under this node.

Examples

let report = check(&Flag, &(), &[])?;
assert_eq!(report.missing()[0].root().arity(), 0);

pub fn fields(&self) -> WitnessFields<'a, T>

The fields under this node, in order.

Examples

let arms = [Arm::new(Pat::product([Pat::bool(false), Pat::bool(false)]))];
let report = check(&Pair, &true, &arms)?;
let first = report.missing()[0].root().fields().next().unwrap();
assert_eq!(first.ctor(), Ctor::Bool(true));

pub fn display<M: Model<Ty = T>>(self, model: &'a M) -> WitnessDisplay<'a, M>

Prints this node with the model’s variant names.

Examples

let report = check(&Opt, &0, &[Arm::new(Pat::variant(1, [Pat::wild()]))])?;
assert_eq!(report.missing()[0].root().display(&Opt).to_string(), "None");

Trait Implementations

impl<T> Clone for WitnessRef<'_, T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Copy for WitnessRef<'_, T>

impl<T> Debug for WitnessRef<'_, T>

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

Formats the value using the given formatter.

impl<T> Display for WitnessRef<'_, T>

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

Prints the subtree in a neutral syntax: #i(..) for variants, tuples for products, _ for wildcards and unnamed values.