Module Compare

 Jan Burse, created Dec 23. 2018 
/**


 * The arithmetic comparisons are more flexible than the lexical


 * comparisons. They are defined for integers, floats and decimals.


 * For decimals comparison across scales is supported. The same


 * widening as already defined for the basic operations applies as well:


 *


 * Examples:


 * 1 < 2


 * 1.0 < 2.0


 * 0d1.00D < 2


 * 1 =:= 0d1.00


 *


 * We also provide evaluable functions min/2 and max/2. These functions are


 * based on the aforementioned arithmetic comparison. The type of the return


 * value depends on the order of the arguments of these evaluable functions.


 *


 * min, max: integer x integer -> integer


 * min, max: float x float -> float


 * min, max: decimal x decimal -> decimal


 * epsilon: float


 *


 * The constant epsilon allows querying the smallest float number that when


 * added to one will still result in a float number different from one


 * without any rounding.


 *


 * Warranty & Liability


 * To the extent permitted by applicable law and unless explicitly


 * otherwise agreed upon, XLOG Technologies GmbH makes no warranties


 * regarding the provided information. XLOG Technologies GmbH assumes


 * no liability that any problems might be solved with the information


 * provided by XLOG Technologies GmbH.


 *


 * Rights & License


 * All industrial property rights regarding the information - copyright


 * and patent rights in particular - are the sole property of XLOG


 * Technologies GmbH. If the company was not the originator of some


 * excerpts, XLOG Technologies GmbH has at least obtained the right to


 * reproduce, change and translate the information.


 *


 * Reproduction is restricted to the whole unaltered document. Reproduction


 * of the information is only allowed for non-commercial uses. Selling,


 * giving away or letting of the execution of the library is prohibited.


 * The library can be distributed as part of your applications and libraries


 * for execution provided this comment remains unchanged.


 *


 * Restrictions


 * Only to be distributed with programs that add significant and primary


 * functionality to the library. Not to be distributed with additional


 * software intended to replace any components of the library.


 *


 * Trademarks


 * Jekejeke is a registered trademark of XLOG Technologies GmbH.


 */




:- use_package(foreign(jekpro/reference/arithmetic)).


:- use_package(foreign(jekpro/frequent/basic)).




:- module(user, []).




:- public infix(=:=).


:- op(700, xfx, =:=).




:- public infix(=\=).


:- op(700, xfx, =\=).




:- public infix(<).


:- op(700, xfx, <).




:- public infix(=<).


:- op(700, xfx, =<).




:- public infix(>).


:- op(700, xfx, >).




:- public infix(>=).


:- op(700, xfx, >=).




/**


 * X =:= Y: [ISO 8.7.1]


 * Succeeds when X arithmetically equals Y, otherwise fails.


 */


% +Expr =:= +Expr


:- public =:= /2.


:- set_predicate_property(=:= /2, (meta_predicate#(1)=:= #(1))).


:- sys_context_property(here, C),


   set_predicate_property(=:= /2, sys_meta_predicate(C)).


:- special(=:= /2, 'SpecialCompare', 0).




/**


 * X =\= Y: [ISO 8.7.1]


 * Succeeds when X does not arithmetically equal Y, otherwise fails.


 */


% +Expr =\= +Expr


:- public =\= /2.


:- set_predicate_property(=\= /2, (meta_predicate#(1)=\= #(1))).


:- sys_context_property(here, C),


   set_predicate_property(=\= /2, sys_meta_predicate(C)).


:- special(=\= /2, 'SpecialCompare', 1).




/**


 * X < Y: [ISO 8.7.1]


 * Succeeds when X is arithmetically less than Y, otherwise fails.


 */


% +Expr < +Expr


:- public < /2.


:- set_predicate_property(< /2, (meta_predicate#(1)< #(1))).


:- sys_context_property(here, C),


   set_predicate_property(< /2, sys_meta_predicate(C)).


:- special(< /2, 'SpecialCompare', 2).




/**


 * X =< Y: [ISO 8.7.1]


 * Succeeds when X is arithmetically less or equal to Y, otherwise fails.


 */


% +Expr =< +Expr


:- public =< /2.


:- set_predicate_property(=< /2, (meta_predicate#(1)=< #(1))).


:- sys_context_property(here, C),


   set_predicate_property(=< /2, sys_meta_predicate(C)).


:- special(=< /2, 'SpecialCompare', 3).




/**


 * X > Y: [ISO 8.7.1]


 * Succeeds when X is arithmetically greater than Y, otherwise fails.


 */


% +Expr > +Expr


:- public > /2.


:- set_predicate_property(> /2, (meta_predicate#(1)> #(1))).


:- sys_context_property(here, C),


   set_predicate_property(> /2, sys_meta_predicate(C)).


:- special(> /2, 'SpecialCompare', 4).




/**


 * X >= Y: [ISO 8.7.1]


 * Succeeds when X is arithmetically greater or equal to Y, otherwise fails.


 */


% +Expr >= +Expr


:- public >= /2.


:- set_predicate_property(>= /2, (meta_predicate#(1)>= #(1))).


:- sys_context_property(here, C),


   set_predicate_property(>= /2, sys_meta_predicate(C)).


:- special(>= /2, 'SpecialCompare', 5).




/**


 * min(X, Y): [TC2 9.3.9]


 * If X and Y are both numbers then the function returns the minimum of X and Y.


 */


% min: integer x integer -> integer


% min: float x float -> float


% min: decimal x decimal -> decimal


:- public min/3.


:- special(min/3, 'EvaluableCompare', 0).




/**


 * max(X, Y): [TC2 9.3.8]


 * If X and Y are both numbers then the function returns the maximum of X and Y.


 */


% max: integer x integer -> integer


% max: float x float -> float


% max: decimal x decimal -> decimal


:- public max/3.


:- special(max/3, 'EvaluableCompare', 1).




/**


 * epsilon: [N208 9.7.3]


 * Returns the ulp of one.


 */


:- public epsilon/1.


% :- foreign_const(epsilon/1, 'SpecialCompare', 'EPSILON').


:- foreign_fun(epsilon/1, 'ForeignHyper', epsilon).

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