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`library(between)`

This library module provides some means of generating integers. Exported predicates:

`between(`

`+Lower`,`+Upper`,`-Number`)-
is true when

`Lower`,`Upper`, and`Number`are integers, and`Lower =< Number =< Upper`. If`Lower`and`Upper`are given,`Number`can be tested or enumerated. If either`Lower`or`Upper`is absent, there is not enough information to find it, and an error will be reported. `gen_nat(`

`?N`)-
is true when

`N`is a natural number. If`N`is a variable, it will enumerate the natural numbers 0,1,2,... and of course not terminate. It is not meant to be applied to anything but integers and variables. `gen_int(`

`?I`)-
is true when I is an integer. If I is a variable, it will enumerate the integers in the order 0, 1, -1, 2, -2, 3, -3, &c. Of course this sequence has no end. It is not meant to be applied to anything but integers and variables.

`repeat(`

`+N`)-
(where

`N`is a non-negative integer) succeeds exactly`N`times. You can only understand it procedurally, and really it is only included for compatibility with some other Prologs. `numlist(`

`?Upper`,`?List`)-
is true when

`List`is the list of integers`[1, ..., Upper]`. For example,`numlist(3,L)`

binds`L = [1,2,3]`

. `numlist(`

`?Lower`,`?Upper`,`?List`)is true when

`List`is`[Lower, ..., Upper]`,`Lower`and`Upper`integers. For example,`numlist(1, 3, L)`

binds`L = [1,2,3]`

.`numlist(`

`?Lower`,`?Step`,`?Upper`,`?Length`,`?List`)is true when

`List`is the list of integers`[Lower, Lower+Step, ..., Upper]`and of length`Length`. For example,`numlist(L,2,U,S,[1,X,Y,Z])`

binds`L=1, S=4, U=7, X=3, U=5, Z=7`

.

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