Section "operators"

To lookup syntax operators we use ordinary Prolog facts. The predicate current_op/3 queries the current system and user syntax operators. The predicate op/3 defines a new operator or updates an existing operator.

The following syntax operators are predefined:

Table 1: Predefined Syntax Operators

Level	Mode	Operators
1200	fx	[:-, ?-, -->]
1200	xfx	[:-]
1150	fx	[dynamic, discontiguous, multifile]
1100	xfy	[;]
1050	xfy	[->]
1000	xfy	[',']
900	fy	[\+]
700	xfx	[is, =, =.., <, =<, =\=, >=, >, =:=, @<, @=<, \==, @>=, @>, ==]
600	xfy	[:]
500	yfx	[+, -, /\, \/]
400	yfx	[*, /, //, rem, xor, >>, <<, div, mod]
200	xfx	[**]
200	xfy	[^]
200	fy	[-, \]

The following syntax operator predicates are provided:

current_op(L, M, O): [ISO 8.14.4]: The predicate succeeds for every operator O with mode M and level L.
op(L, M, O): [ISO 8.14.3]: The predicate succeeds. As a side effect, a new operator O with mode M and level L is asserted.