left associative with precedence 55
for @{ 'divide $a $b }.
-notation "- a"
+notation > "- a"
right associative with precedence 60
for @{ 'uminus $a }.
+notation < "- a"
+ right associative with precedence 75
+for @{ 'uminus $a }.
+
notation "a !"
non associative with precedence 80
for @{ 'fact $a }.