Enum InvalidConstraintKind 

pub enum InvalidConstraintKind {
    Variable(Name),
    Unapplied(Name),
    Arrow,
    Tuple,
    Unit,
    Record,
}

What was written in front of => in place of a constraint — see Error::InvalidConstraint.

A constraint is an uppercase name applied to one or more type arguments, and a context is one constraint or a parenthesised, comma-separated list of them ([parser::Context]). This names every other shape an element of that list can take, one per remaining [parser::TypeKind] case.

Variants

Variable(Name)

A type variable on its own — a => a.

Unapplied(Name)

An uppercase name with no argument — Int => a, and so each half of (Int, Char) => a. Carries the name so the message can quote it.

Arrow

A function type — Int -> Int => a.

Tuple

A tuple inside the parenthesised list — ((Eq a, Eq b), Eq c) => a. The parser reads the outermost parentheses as the list, so only a tuple nested in it reaches here.

Unit

The unit type — () => a.

Record

A record type — { x : a } => a.

Trait Implementations

impl Clone for InvalidConstraintKind

fn clone(&self) -> InvalidConstraintKind

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for InvalidConstraintKind

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

Formats the value using the given formatter.

impl PartialEq for InvalidConstraintKind

fn eq(&self, other: &InvalidConstraintKind) -> bool

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for InvalidConstraintKind