conj :: Disjunction -> Disjunction -> Disjunction
Disjunction dps `conj` Disjunction dqs = Disjunction [ps `conj'` qs | ps <- dps, qs <- dqs]
conj :: Disjunction -> Disjunction -> Disjunction
Disjunction dps `conj` Disjunction dqs = Disjunction [ps `conj'` qs | ps <- dps, qs <- dqs]
Disjunction dps `conj` Disjunction dqs = Disjunction [ps `conj'` qs | ps <- dps, qs <- dqs]