Lorentz.ReferencedByName

Referenced-by-name versions of some instructions.

They allow to "dig" into stack or copy elements of stack referring them by label.

Constraints

class HasNamedVar (s :: [Type]) (name :: Symbol) (var :: Type) | s name -> var

Indicates that stack s contains a name :! var or name :? var value.

Minimal complete definition

varPosition

Instances

(TypeError (StackElemNotFound name) :: Constraint, var ~ NamedVariableNotFound name) => HasNamedVar ('[] :: [Type]) name var

Defined in Lorentz.ReferencedByName

Methods

varPosition :: VarPosition '[] name var

ElemHasNamedVar (ty ': s) name var (VarNamePretty ty == 'VarNamed name) => HasNamedVar (ty ': s) name var

Defined in Lorentz.ReferencedByName

Methods

varPosition :: VarPosition (ty ': s) name var

type family HasNamedVars (s :: [Type]) (vs :: [NamedField]) :: Constraint where ...

Version of HasNamedVar for multiple variables.

>>> type HasContext = HasNamedVars s ["x" := Integer, "f" := Lambda MText MText]

Equations

HasNamedVars _ '[] = ()

HasNamedVars s ((n := ty) ': vs) = (HasNamedVar s n ty, HasNamedVars s vs)

type (:=) n ty = 'NamedField n ty infixr 0

Instructions

dupL :: forall var name s. HasNamedVar s name var => Label name -> s :-> (var ': s)

Take the element with given label on stack and copy it on top.

If there are multiple variables with given label, the one closest to the top of the stack is picked.

dupLNamed :: forall var name s. HasNamedVar s name var => Label name -> s :-> ((name :! var) ': s)

Version of dupL that leaves a named variable on stack.

Other

type VarIsUnnamed x = VarName x ~ 'VarUnnamed

Requires type x to be an unnamed variable.

When e.g. dupL sees a polymorphic variable, it can't judge whether is it a variable we are seeking for or not; VarIsUnnamed helps to assure the type system that given variable won't be named.