The following table lists all of Mercury’s builtin operators.
Operators with a low “Priority” bind more tightly
than those with a high “Priority”.
For example, given that
+ has priority 500 and * has priority 400,
the term 2 * X + Y would parse as (2 * X) + Y.
The “Specifier” field indicates what structure terms constructed with an operator are allowed to take. “f” represents the operator and “x” and “y” represent arguments. “x” represents an argument whose priority must be strictly lower than that of the operator. “y” represents an argument whose priority is lower or equal to that of the operator. For example, “yfx” indicates a left-associative infix operator, while “xfy” indicates a right-associative infix operator.
Operator Specifier Priority . yfx 10 ! fx 40 !. fx 40 !: fx 40 @ xfx 90 ^ xfy 99 ^ fx 100 event fx 100 : yfx 120 `op` yfx 120 (1) ** xfy 200 - fx 200 \ fx 200 * yfx 400 / yfx 400 // yfx 400 << yfx 400 >> yfx 400 div yfx 400 mod xfx 400 rem xfx 400 for xfx 500 + fx 500 + yfx 500 ++ xfy 500 - yfx 500 -- yfx 500 /\ yfx 500 \/ yfx 500 .. xfx 550 := xfx 650 =^ xfx 650 < xfx 700 = xfx 700 =.. xfx 700 =:= xfx 700 =< xfx 700 == xfx 700 =\= xfx 700 > xfx 700 >= xfx 700 @< xfx 700 @=< xfx 700 @> xfx 700 @>= xfx 700 \= xfx 700 \== xfx 700 ~= xfx 700 is xfx 701 and xfy 720 or xfy 740 func fx 800 impure fy 800 pred fx 800 semipure fy 800 \+ fy 900 not fy 900 when xfx 900 ~ fy 900 <= xfy 920 <=> xfy 920 => xfy 920 all fxy 950 arbitrary fxy 950 atomic fxy 950 disable_warning fxy 950 disable_warnings fxy 950 promise_equivalent_solutions fxy 950 promise_equivalent_solution_sets fxy 950 promise_exclusive fy 950 promise_exclusive_exhaustive fy 950 promise_exhaustive fy 950 promise_impure fx 950 promise_pure fx 950 promise_semipure fx 950 require_complete_switch fxy 950 require_switch_arms_det fxy 950 require_switch_arms_semidet fxy 950 require_switch_arms_multi fxy 950 require_switch_arms_nondet fxy 950 require_switch_arms_cc_multi fxy 950 require_switch_arms_cc_nondet fxy 950 require_switch_arms_erroneous fxy 950 require_switch_arms_failure fxy 950 require_det fx 950 require_semidet fx 950 require_multi fx 950 require_nondet fx 950 require_cc_multi fx 950 require_cc_nondet fx 950 require_erroneous fx 950 require_failure fx 950 trace fxy 950 try fxy 950 some fxy 950 , xfy 1000 & xfy 1025 -> xfy 1050 ; xfy 1100 or_else xfy 1100 then xfx 1150 if fx 1160 else xfy 1170 :: xfx 1175 ==> xfx 1175 where xfx 1175 ---> xfy 1179 catch xfy 1180 type fx 1180 solver fy 1181 catch_any xfy 1190 end_module fx 1199 import_module fx 1199 include_module fx 1199 initialise fx 1199 initialize fx 1199 finalise fx 1199 finalize fx 1199 inst fx 1199 instance fx 1199 mode fx 1199 module fx 1199 pragma fx 1199 promise fx 1199 rule fx 1199 typeclass fx 1199 use_module fx 1199 --> xfx 1200 :- fx 1200 :- xfx 1200 ?- fx 1200