number_merge(+List1, +List2, -List3)

List1

List of numeric terms.

List2

List of numeric terms.

List3

List of numeric terms or variable.

Description

For two lists [e1,e2,e3] and [f1,f2,f3], e1 is compared to f1. The lower (dictated by numerical ordering) is put into List3, and the process continued with the remaining input lists. This process continues until both lists are exhausted.

In particular, this will merge two sorted lists into a sorted list.

The sort is done according to numerical ordering of terms as opposed to merge/3 which uses the standard ordering of terms. Duplicates are not removed. See sort/4 for a discussion of the differences between numerical and standard ordering of numeric types.

number_merge(A, B, M) is equivalent to merge(0, $=<, A, B, M).

Modes and Determinism

• number_merge(+, +, -) is det

Exceptions

(4) instantiation fault

List1 or List2 is not ground.

(5) type error

List1 or List2 contains non-numeric elements.

Examples

Success:
      number_merge([2,4,6],[1,3,5],L).
                            (gives L=[1,2,3,4,5,6]).
      number_merge([f(1),f(7)],[f(8),f(10)],L).
                          (gives L=[f(1),f(7),f(8),f(10)]).
      number_merge([f(5),f(8)],[f(1),f(2),f(2),f(5),f(8)],L).
            (gives L=[f(1),f(2),f(2),f(5),f(5),f(8),f(8)]).
      number_merge([a,w],[a,b,b,r,w],L).
            (gives L=[a,a,b,b,r,w,w]).
      number_merge([f(2),f(1)],[f(3),f(8)],L).
            (gives L=[f(2),f(1),f(3),f(8)]).

Fail:
      number_merge([2,4,6],[1,3,5],[1,2,3,4,5]).

See Also