Enum VarKind 

pub enum VarKind {
    Type,
    EnumRows {
        excluded: HashSet<Ident>,
    },
    RecordRows {
        excluded: HashSet<Ident>,
    },
}

The kind of a quantified type variable.

Nickel uses several forms of polymorphism. A type variable can be substituted for a type, as in id : forall a. a -> a, for record rows as in access_foo : forall a . {foo : Number; a} -> Number}, or for enum rows. This information is implicit in the source syntax: we don’t require users to write e.g. forall a :: Type or forall a :: Rows. But the kind of a variable is required for the typechecker. It is thus determined during parsing and stored as VarKind where type variables are introduced, that is, on forall quantifiers.

Variants

Type

EnumRows

excluded keeps track of which rows appear somewhere alongside the tail, and therefore cannot appear in the tail. For instance forall r. { ; r } -> { x : Number ; r } assumes

Fields

excluded: HashSet<Ident>

RecordRows

Same as for Self::EnumRows.

Fields

excluded: HashSet<Ident>

Trait Implementations

impl Clone for VarKind

fn clone(&self) -> VarKind

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for VarKind

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

Formats the value using the given formatter.

impl Default for VarKind

fn default() -> VarKind

Returns the “default value” for a type.

impl From<&VarKind> for VarKindDiscriminant

fn from(vk: &VarKind) -> Self

Converts to this type from the input type.

impl PartialEq for VarKind

fn eq(&self, other: &VarKind) -> 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.

impl Eq for VarKind

impl StructuralPartialEq for VarKind