Capabilities

Map each occurrence of cap to a different Fresh instance Exception: CapSet^ stays as it is.

Attributes

Supertypes: trait FollowAliasesMap

trait BiTypeMap

class TypeMap

trait Type => Type

class VariantTraversal

class Object

trait Matchable

class Any
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Self type: CapToFresh

A trait for references in CaptureSets. These can be NamedTypes, ThisTypes or ParamRefs, as well as three kinds of AnnotatedTypes representing readOnly, reach, and maybe capabilities. If there are several annotations they come with an order: * first, .rd next, ? last.

Attributes

Supertypes: trait Showable

class Object

trait Matchable

class Any
Known subtypes: trait CoreCapability

trait ObjectCapability

class TermParamRef

class TermRef

class CachedTermRef

class ThisType

class CachedThisType

trait SetCapability

class TypeParamRef

class TypeRef

class CachedTypeRef

class ParamRef

trait DerivedCapability

class Maybe

class Reach

class ReadOnly

trait RootCapability

class FreshCap

object GlobalCap

class ResultCap
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The base trait of all capabilties represented as types

Attributes

Supertypes: trait Capability

class TypeProxy

class Type

trait Showable

trait Hashable

class Object

trait Matchable

class Any
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Known subtypes: trait ObjectCapability

class TermParamRef

class TermRef

class CachedTermRef

class ThisType

class CachedThisType

trait SetCapability

class TypeParamRef

class TypeRef

class CachedTypeRef

class ParamRef
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Attributes

Supertypes: trait Capability

trait Showable

class Object

trait Matchable

class Any
Known subtypes: class Maybe

class Reach

class ReadOnly

The class of "fresh" roots. These do subsume other capabilties in scope. They track with hidden sets which other capabilities were subsumed. Hidden sets are inspected by separation checking.

Value parameters

origin: an indication where and why the FreshCap was created, used for diagnostics
owner: the owner of the context in which the FreshCap was created

Attributes

Companion: object
Supertypes: trait Serializable

trait Product

trait Equals

trait RootCapability

trait Capability

trait Showable

class Object

trait Matchable

class Any
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Attributes

Companion: class
Supertypes: class Object

trait Matchable

class Any
Self type: FreshCap.type

The global root capability referenced as caps.cap cap does not subsume other capabilities, except in arguments of withCapAsRoot calls.

Attributes

Supertypes: trait RootCapability

trait Capability

trait Showable

class Object

trait Matchable

class Any
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Self type: GlobalCap.type

If x is a capability, its maybe capability x?. x? stands for a capability x that might or might not be part of a capture set. We have {} <: {x?} <: {x}. Maybe capabilities cannot be propagated between sets. If a <: b and a acquires x? then x is propagated to b as a conservative approximation.

Maybe capabilities should only arise for capture sets that appear in invariant position in their surrounding type. They are similar to TypeBounds types, but restricted to capture sets. For instance,

Array[C^{x?}]

should be morally equivalent to

Array[_ >: C^{} <: C^{x}]

but it has fewer issues with type inference.

Attributes

Supertypes: trait Serializable

trait Product

trait Equals

trait DerivedCapability

trait Capability

trait Showable

class Object

trait Matchable

class Any
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Attributes

Supertypes: trait CoreCapability

trait Capability

class TypeProxy

class Type

trait Showable

trait Hashable

class Object

trait Matchable

class Any
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Known subtypes: class TermParamRef

class TermRef

class CachedTermRef

class ThisType

class CachedThisType

The place of - and cause for - creating a fresh capability. Used for error diagnostics

Attributes

Supertypes: trait Enum

trait Serializable

trait Product

trait Equals

class Object

trait Matchable

class Any
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If x is a capability, its reach capability x*. x* stands for all capabilities reachable through x. We have {x} <: {x*} <: dcs(x)} where the deep capture set dcs(x) of x is the union of all capture sets that appear in covariant position in the type of x. If x and y are different variables then {x*} and {y*} are unrelated.

Reach capabilities cannot wrap read-only capabilities or maybe capabilities. We have (x.rd).reach = x*.rd (x.rd)? = (x*)?

Attributes

Supertypes: trait Serializable

trait Product

trait Equals

trait DerivedCapability

trait Capability

trait Showable

class Object

trait Matchable

class Any
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The readonly capability x.rd. We have {x.rd} <: {x}.

Read-only capabilities cannot wrap maybe capabilities but they can wrap reach capabilities. We have (x?).readOnly = (x.rd)?

Attributes

Supertypes: trait Serializable

trait Product

trait Equals

trait DerivedCapability

trait Capability

trait Showable

class Object

trait Matchable

class Any
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A root capability associated with a function type. These are conceptually existentially quantified over the function's result type.

Value parameters

binder: The function type with which the capability is associated. It is a MethodicType since we also have ResultCaps that are associated with the ExprTypes of parameterless functions. Currently we never create results over PolyTypes. TODO change this? Setup: In the setup phase, cap instances in the result of a dependent function type or method type such as (x: T): C^{cap} are converted to ResultCap(binder) instances, where binder refers to the method type. Most other cap instances are mapped to Fresh instances instead. For example the cap in the result of T => C^{cap} is mapped to a Fresh instance. If one needs to use a dependent function type yet one still want to map cap to a fresh instance instead an existential root, one can achieve that by the use of a type alias. For instance, the following type creates an existential for ^: (x: A) => (C^{x}, D^) By contrast, this variant creates a fresh instance instead: type F[X] = (x: A) => (C^{x}, X) F[D^] The trick is that the argument D^ is mapped to D^{fresh} before the F alias is expanded.

Attributes

Supertypes: trait Serializable

trait Product

trait Equals

trait RootCapability

trait Capability

trait Showable

class Object

trait Matchable

class Any
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The base trait of all root capabilities

Attributes

Supertypes: trait Capability

trait Showable

class Object

trait Matchable

class Any
Known subtypes: class FreshCap

object GlobalCap

class ResultCap

Attributes

Supertypes: trait CoreCapability

trait Capability

class TypeProxy

class Type

trait Showable

trait Hashable

class Object

trait Matchable

class Any
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Known subtypes: class TypeParamRef

class TypeRef

class CachedTypeRef

Capabilities

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