Defining operators
Author(s): Daniel Cabeza (modifications and documentation, adapted from SICStus 0.6 code), Manuel Carro (modifications and documentation).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
- Library usage:
:- use_module(library(operators)). - Exports:
- Predicates:
op/3, current_op/3, current_prefixop/3, current_infixop/4, current_postfixop/3, standard_ops/0.
- Predicates:
- Imports:
- Packages:
prelude, nonpure, assertions, isomodes.
- Packages:
Documentation on exports
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:
(basic_props:int/1)Precedence is an integer.
(basic_props:operator_specifier/1)Type specifies the type and associativity of an operator.
(basic_props:atm_or_atm_list/1)Name is an atom or a list of atoms. - The following properties should hold globally:
(basic_props:native/1)This predicate is understood natively by CiaoPP.
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
- Call and exit should be compatible with:
(basic_props:int/1)Precedence is an integer.
(basic_props:operator_specifier/1)Type specifies the type and associativity of an operator.
(basic_props:atm/1)Op is an atom. - The following properties should hold upon exit:
(basic_props:int/1)Precedence is an integer.
(basic_props:operator_specifier/1)Type specifies the type and associativity of an operator.
(basic_props:atm/1)Op is an atom. - The following properties should hold globally:
(basic_props:native/1)This predicate is understood natively by CiaoPP.
Similar to current_op/3, but it concerns only the prefix operators. It returns only one solution. Not a predicate for general use.
Usage:
- Call and exit should be compatible with:
(basic_props:atm/1)Op is an atom.
(basic_props:int/1)Less is an integer.
(basic_props:int/1)Precedence is an integer. - The following properties should hold upon exit:
(basic_props:atm/1)Op is an atom.
(basic_props:int/1)Less is an integer.
(basic_props:int/1)Precedence is an integer. - The following properties should hold globally:
(basic_props:native/1)This predicate is understood natively by CiaoPP.
Similar to current_op/3, but it concerns only infix operators. It returns only one solution. Not a predicate for general use.
Usage:
- Call and exit should be compatible with:
(basic_props:atm/1)Op is an atom.
(basic_props:int/1)LeftLess is an integer.
(basic_props:int/1)Prec is an integer.
(basic_props:int/1)RightLess is an integer. - The following properties should hold upon exit:
(basic_props:atm/1)Op is an atom.
(basic_props:int/1)LeftLess is an integer.
(basic_props:int/1)Prec is an integer.
(basic_props:int/1)RightLess is an integer. - The following properties should hold globally:
(basic_props:native/1)This predicate is understood natively by CiaoPP.
Similar to current_op/3, but it concerns only the postfix operators. It returns only one solution. Not a predicate for general use.
Usage:
- Call and exit should be compatible with:
(basic_props:atm/1)Op is an atom.
(basic_props:int/1)Less is an integer.
(basic_props:int/1)Precedence is an integer. - The following properties should hold upon exit:
(basic_props:atm/1)Op is an atom.
(basic_props:int/1)Less is an integer.
(basic_props:int/1)Precedence is an integer. - The following properties should hold globally:
(basic_props:native/1)This predicate is understood natively by CiaoPP.
