Since you did not give any example queries, start with some example queries to determine the parameters and output format. Normally to determine the parameters and output format for unknown code requires looking at the code for the structure of the arguments and then trying sample queries. Additionally note that this code uses the Constraint … Read more
Use CLP(FD) constraints, for example: :- use_module(library(clpfd)). binary_number(Bs0, N) :- reverse(Bs0, Bs), foldl(binary_number_, Bs, 0-0, _-N). binary_number_(B, I0-N0, I-N) :- B in 0..1, N #= N0 + B*2^I0, I #= I0 + 1. Example queries: ?- binary_number([1,0,1], N). N = 5. ?- binary_number(Bs, 5). Bs = [1, 0, 1] . ?- binary_number(Bs, N). Bs = … Read more
The recursive part is not quite correct. split([], [], []). split([Head|Tail], [Head|List1], List2) :- Head>=0, split(Tail, List1, List2). split([Head|Tail], List1, [Head|List2]) :- Head<0, split(Tail, List1, List2). The Head should be added to the positive list if Head >= 0 and to the negative list when Head < 0. Moreover, checking the sign of Head at … Read more
Consider using finite domain constraints, for example, in SWI-Prolog: :- use_module(library(clpfd)). puzzle([S,E,N,D] + [M,O,R,E] = [M,O,N,E,Y]) :- Vars = [S,E,N,D,M,O,R,Y], Vars ins 0..9, all_different(Vars), S*1000 + E*100 + N*10 + D + M*1000 + O*100 + R*10 + E #= M*10000 + O*1000 + N*100 + E*10 + Y, M #\= 0, S #\= 0. … Read more
What’s probably more useful than a slightly less nondeterministic length/2 is a proper list-length constraint. You can find an ECLiPSe implementation of it here, called len/2. With this you get the following behaviour: ?- N :: 1..3, len(Xs, N). N = N{1 .. 3} Xs = [_431|_482] % note it must contain at least one … Read more
Here’s how you can find the “powers of two” in logically-pure way! Using sicstus-prolog 4.3.5, library(reif) and library(clpz): :- use_module([library(reif), library(clpz)]). power_of_two_t(I, T) :- L #= min(I,1), M #= I /\ (I-1), call((L = 1, M = 0), T). % using (=)/3 and (‘,’)/3 of library(reif) Sample query1 using meta-predicate tfilter/3 in combination with power_of_two_t/2: … Read more
Hoogle was not very useful, but Hayoo is! foldcmpl so this is a special form of fold for a list, but it does not apply length list times but one time less. isSortedBy is not entirely general in its name, but in its signature. Maybe insisting on the most general name is not that helpful. … Read more