5 #include <AD/strings/quark.h>
7 datatype Wff :: rewrite
10 | Var (class Quark) => _
11 | Op (class Quark, Wff, Wff) => "(" 2 1 3 ")"
12 | Not (Wff) => "not(" _ ")"
15 inline And(a,b) = Op(#"and",a,b)
16 and inline Or(a,b) = Op(#"or",a,b)
17 and inline Implies(a,b) = Op(#"->",a, b)
18 and inline Xor(a,b) = Op(#"xor",a,b)
19 and inline Equiv(a,b) = Op(#"<->",a,b)