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package hamlet
import "reflect"
type Assertion struct {
truth bool
}
func (a Assertion) Assert() bool {
return a.truth
}
func (a Assertion) Deny() bool {
return !a.truth
}
func Present(v any) Assertion {
return Assertion{!reflect.ValueOf(v).IsZero()}
}
func Absent(v any) Assertion {
return Assertion{reflect.ValueOf(v).IsZero()}
}
// Not computes ~a, given assertion a.
func Not(a Assertion) Assertion {
negation := !a.truth
return Assertion{negation}
}
// Or computes a v b, given assertions a and b.
func Or(a Assertion, b Assertion) Assertion {
av := a.truth
bv := b.truth
return Assertion{av || bv}
}
// And computes a ^ b, given assertions a and b.
func And(a Assertion, b Assertion) Assertion {
av := a.truth
bv := b.truth
return Assertion{av && bv}
}
// If computes a → b, given assertions a and b.
func If(a Assertion, b Assertion) Assertion {
return Or(Not(a), b)
}
// If computes a ↔ b, given assertions a and b.
func Iff(a Assertion, b Assertion) Assertion {
return And(If(a, b), If(b, a))
}
// Xor computes a ⊻ b, given assertions a and b.
func Xor(a Assertion, b Assertion) Assertion {
return Not(Iff(a, b))
}
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