Struct TypeVariable 

pub struct TypeVariable { /* private fields */ }

A type variable: a placeholder unify may solve to a type, or a rigid one, which it may not.

A flexible variable is the inference variable of an expression, and the variable of a declared type a use instantiates. A rigid variable is one the declaration being checked is universally quantified over: the variables its annotation wrote, or the variables of an instance’s head and of the member signature its bindings are held to (make_rigid makes them). It stands for every type a caller may choose, so it is equal to itself and to nothing else, and unifier::unify raises ErrorKind::RigidVariable where a body would need it to be anything more specific.

A rigid variable is a flexible one’s id with the name the source wrote it by, which is what a message writes it as. The id is what tells two variables apart: two rigid variables may be written alike, as an instance’s head and the member signature its binding is held to each write their own.

A rigid variable belongs to the declaration whose body is checked: the types of the term that comes back hold it, and nothing the environment holds for another declaration does. What the environment holds for a use, a Scheme, is over flexible variables, which each use instantiates fresh.

Trait Implementations

impl Clone for TypeVariable

fn clone(&self) -> TypeVariable

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TypeVariable

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

Formats the value using the given formatter.

impl Eq for TypeVariable

impl Hash for TypeVariable

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for TypeVariable

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for TypeVariable