Agda-2.5.1.2: A dependently typed functional programming language and proof assistant

Safe HaskellNone
LanguageHaskell98

Agda.TypeChecking.Positivity.Occurrence

Description

Occurrences.

Synopsis

Documentation

data Occurrence Source #

Subterm occurrences for positivity checking. The constructors are listed in increasing information they provide: Mixed <= JustPos <= StrictPos <= GuardPos <= Unused Mixed <= JustNeg <= Unused.

Constructors

Mixed

Arbitrary occurrence (positive and negative).

JustNeg

Negative occurrence.

JustPos

Positive occurrence, but not strictly positive.

StrictPos

Strictly positive occurrence.

GuardPos

Guarded strictly positive occurrence (i.e., under ∞). For checking recursive records.

Unused 

Instances

Bounded Occurrence Source # 
Enum Occurrence Source # 
Eq Occurrence Source # 
Ord Occurrence Source # 
Show Occurrence Source # 
Arbitrary Occurrence Source # 
CoArbitrary Occurrence Source # 

Methods

coarbitrary :: Occurrence -> Gen b -> Gen b #

NFData Occurrence Source # 

Methods

rnf :: Occurrence -> () #

StarSemiRing Occurrence Source # 
SemiRing Occurrence Source #

Occurrence is a complete lattice with least element Mixed and greatest element Unused.

It forms a commutative semiring where oplus is meet (glb) and otimes is composition. Both operations are idempotent.

For oplus, Unused is neutral (zero) and Mixed is dominant. For otimes, StrictPos is neutral (one) and Unused is dominant.

Null Occurrence Source # 
KillRange Occurrence Source # 
PrettyTCM Occurrence Source # 
Abstract [Occurrence] Source # 
Apply [Occurrence] Source # 
PrettyTCM n => PrettyTCM (WithNode n Occurrence) Source # 

boundToEverySome :: Map Occurrence [(Occurrence -> Bool, Occurrence -> Bool)] Source #

The map contains bindings of the form bound |-> es, satisfying the following property: for every non-empty list w, foldr1 otimes w <= bound iff or [ all every w && any some w | (every, some) <- ess ].

productOfEdgesInBoundedWalk :: (SemiRing e, Ord n) => (e -> Occurrence) -> Graph n n e -> n -> n -> Occurrence -> Maybe e Source #

productOfEdgesInBoundedWalk occ g u v bound returns Just e iff there is a walk c (a list of edges) in g, from u to v, for which the product foldr1 otimes (map occ c) <= bound. In this case the returned value e is the product foldr1 otimes c for one such walk.

Preconditions: u and v must belong to g, and bound must belong to the domain of boundToEverySome.

tests :: IO Bool Source #

Tests.