Defining operators

Author(s): Adapted from SICStus 0.6 code; modifications and documentation by Daniel Cabeza and Manuel Carro.

Version: 1.11#222 (2004/5/24, 13:8:7 CEST)

Version of last change: 1.9#287 (2004/2/13, 18:59:4 CET)

Operators allow writting terms in a more clear way than the standard functional notation. Standard operators in Ciao are defined by this predicate (but note that the compiler itself defines more operators at compile time):

standard_ops :-
        op(1200,xfx,[:-]),
        op(1200,fx,[:-,?-]),
        op(1100,xfy,[;]),
        op(1050,xfy,[->]),
        op(1000,xfy,[',']),
        op(900,fy,[\+]),
        op(700,xfx,[=,\=,==,\==,@<,@>,@=<,@>=,=..,is,=:=,=\=,<,=<,>,>=]),
        op(550,xfx,[:]),
        op(500,yfx,[+,-,/\,\/,#]),
        op(500,fy,[++,--]),
        op(400,yfx,[*,/,//,rem,mod,<<,>>]),
        op(200,fy,[+,-,\]),
        op(200,xfx,[**]),
        op(200,xfy,[^]).

• Usage and interface (operators)
• Documentation on exports (operators)

Usage and interface (operators)

Documentation on exports (operators)

PREDICATE: op/3:

op(Precedence, Type, Name)

Declares the atom Name to be an operator of the stated Type and Precedence (0 =< Precedence =< 1200). Name may also be a list of atoms in which case all of them are declared to be operators. If Precedence is 0 then the operator properties of Name (if any) are cancelled. Note that, unlike in ISO-Prolog, it is allowed to define two operators with the same name, one infix and the other postfix.

Usage: * ISO *

• The following properties should hold at call time: Precedence is an integer. (basic_props:int/1) Type specifies the type and associativity of an operator. (basic_props:operator_specifier/1) Name is an atom or a list of atoms. (basic_props:atm_or_atm_list/1)
• The following properties hold globally: This predicate is understood natively by CiaoPP. (basic_props:native/1)

PREDICATE: current_op/3:

current_op(Precedence, Type, Op)

The atom Op is currently an operator of type Type and precedence Precedence. Neither Op nor the other arguments need be instantiated at the time of the call; i.e., this predicate can be used to generate as well as to test.

Usage: * ISO *

• Calls should, and exit will be compatible with: Precedence is an integer. (basic_props:int/1) Type specifies the type and associativity of an operator. (basic_props:operator_specifier/1) Op is an atom. (basic_props:atm/1)
• The following properties hold upon exit: Precedence is an integer. (basic_props:int/1) Type specifies the type and associativity of an operator. (basic_props:operator_specifier/1) Op is an atom. (basic_props:atm/1)
• The following properties hold globally: This predicate is understood natively by CiaoPP. (basic_props:native/1)

PREDICATE: current_prefixop/3:

current_prefixop(Op, Less, Precedence)

Similar to current_op/3, but it concerns only the prefix operators. It returns only one solution. Not a predicate for general use.

PREDICATE: current_infixop/4:

current_infixop(Op, LeftLess, Prec, RightLess)

Similar to current_op/3, but it concerns only infix operators. It returns only one solution. Not a predicate for general use.

PREDICATE: current_postfixop/3:

current_postfixop(Op, Less, Precedence)

Similar to current_op/3, but it concerns only the postfix operators. It returns only one solution. Not a predicate for general use.

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