The Fortress Language Specification - CiteSeerX

24.1.10 opr ≡(self,other: Boolean):Boolean
24.1.11 opr =(self,other: Boolean):Boolean
24.1.12 opr ↔(self,other: Boolean):Boolean
The logical equivalence, or exclusive NOR, operator ≡ ( EQV ) returns true if both arguments are true or both
arguments are false ; it returns false if the arguments are different, one being true and the other false . (Thus its
behavior on boolean values happens to be exactly the same as that of the strict equivalence operator = .)
The equality operator = and the if-and-only-if operator ↔ ( IFF ) do the same thing as ≡ .
For ≢ see Section 26.1.2. For ≠ see Section 26.1.4.
24.1.13 opr →(self,other: Boolean):Boolean
24.1.14 opr →(self,other: () → Boolean): Boolean
The logical implication operator → ( IMPLIES ) returns false if the first argument is true but the second argument
is false ; otherwise it returns true .
The conditional logical implication operator → : ( IMPLIES: ) examines its first argument; if it is false , the result
is true , and the second argument (a thunk) is not evaluated. But if the first argument is true , the second argument is
evaluated and its result becomes the result of the conditional logical implication operator expression.
24.1.15 opr ∧(self,other: Boolean):Boolean
The logical NAND (NOT AND) operator ∧ ( NAND ) returns false if both arguments are true ; otherwise it returns
true .
24.1.16 opr ∨(self,other: Boolean):Boolean
The logical NOR (NOT OR) operator ∨ ( NOR ) returns false if both arguments are false ; otherwise it returns true .
24.1.17 getter true():Boolean
24.1.18 getter false():Boolean
The getter true returns the value true , and the getter false returns the value false . These are defined primarily for
the benefit of the BooleanAlgebra traits that Boolean extends.
24.1.19 opr =(self,other: Boolean):Boolean
Two boolean values are strictly equivalent if and only if they are the same boolean value (that is, both true or both
false ).
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