This module provides the XSB
basics module. The implementation either
simply uses SWI-Prolog built-ins and libraries or is copied from the XSB
- - LGPLv2
- for(?I, +B1, +B2)
- Nondeterministically binds I to all integer values from B1 to B2
inclusive. B1 and B2 must be integers, but either may be larger.
- ith(?Index, +List, ?Element)
The following predicates are re-exported from other modules
- subset(+SubSet, +Set) is semidet
- True if all elements of SubSet belong to Set as well. Membership
test is based on memberchk/2. The complexity is |SubSet|*|Set|. A
set is defined to be an unordered list without duplicates.
Elements are considered duplicates if they can be unified.
- See also
- - ord_subset/2.
- flatten(+NestedList, -FlatList) is det
- Is true if FlatList is a non-nested version of NestedList. Note
that empty lists are removed. In standard Prolog, this implies
that the atom '' is removed too. In SWI7,
 is distinct
Ending up needing flatten/2 often indicates, like append/3 for
appending two lists, a bad design. Efficient code that generates
lists from generated small lists must use difference lists,
often possible through grammar rules for optimal readability.
- See also
- - append/2
- reverse(?List1, ?List2)
- Is true when the elements of List2 are in reverse order compared to
List1. This predicate is deterministic if either list is a proper
list. If both lists are partial lists backtracking generates
increasingly long lists.
- select(?Elem, ?List1, ?List2)
- Is true when List1, with Elem removed, results in List2. This
implementation is determinsitic if the last element of List1 has
- append(?List1, ?List2, ?List1AndList2)
- List1AndList2 is the concatenation of List1 and List2
- member(?Elem, ?List)
- True if Elem is a member of List. The SWI-Prolog definition
differs from the classical one. Our definition avoids unpacking
each list element twice and provides determinism on the last
element. E.g. this is deterministic:
- - Gertjan van Noord
The following predicates are exported, but not or incorrectly documented.
- comma_append(Arg1, Arg2, Arg3)
- logk_ith(Arg1, Arg2, Arg3, Arg4)
- comma_member(Arg1, Arg2)
- comma_length(Arg1, Arg2)
- memberchk(Arg1, Arg2)
- abscomma_memberchk(Arg1, Arg2)
- subseq(Arg1, Arg2, Arg3)
- log_ith_new(Arg1, Arg2, Arg3)
- log_ith_to_list(Arg1, Arg2)
- log_ith(Arg1, Arg2, Arg3)
- log_ith_bound(Arg1, Arg2, Arg3)
- comma_memberchk(Arg1, Arg2)
- between(Arg1, Arg2, Arg3)
- comma_to_list(Arg1, Arg2)