Struct Scheme 

pub struct Scheme {
    pub vars: Vec<TyVarId>,
    pub row_vars: Vec<RowVarId>,
    pub params: Vec<Arc<str>>,
    pub ty: Ty,
}

A type scheme: forall vars rows. ty. Let-polymorphism over both dimensions, which is what §3.2 means by “effect polymorphism is what keeps one standard library”.

Fields

vars: Vec<TyVarId>

row_vars: Vec<RowVarId>

params: Vec<Arc<str>>

The named type parameters of a user-written def map[T, U](…).

A prelude scheme quantifies over numbered variables because nobody reads its source; a user’s quantifies over names, because the name is what the programmer wrote, what the body is checked against, what a diagnostic has to print, and what beck iface publishes. Inside the body each of these is a rigid Ty::Con(name, []) — an opaque type that unifies with itself and nothing else, which is exactly the property that makes the definition honest about being polymorphic. Subst::instantiate turns them back into fresh variables at every call site. docs/32 §32.7.

ty: Ty

Implementations

impl Scheme

pub fn mono(ty: Ty) -> Scheme

pub fn generic(params: Vec<Arc<str>>, ty: Ty) -> Scheme

A scheme over named type parameters — what a def with a [T, U] list gets.

Trait Implementations

impl Clone for Scheme

fn clone(&self) -> Scheme

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Scheme

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

Formats the value using the given formatter.