CODEWITHSUNDEEP
prolog
Daniel Bozinovski
Daniel Bozinovski

Reputation: 107

Prolog - How to replace certain words in a list

I have the following prolog predicate:

processWords([hello, my, name, is, Simon], Result).

I need to know how I could get:

Result = [bye, my, name, is, Ben]

How would I recurse through the list and return a string that replaces "hello" with "bye" and "Simon" with "Ben", using Prolog?

Any help is greatly appreciated, thanks!

Upvotes: 0

Views: 454

Answers (1)

tiffi
tiffi

Reputation: 683

First of all, this cannot be done, since "Simon" and "Ben" in your example are variables. But supposing you are fine with "simon" and "ben", here is an answer:

processWords([], []).

processWords([H|T], [H2|T2]) :-
    translate(H, H2),
    processWords(T, T2).

translate(hello, bye):-!.
translate(simon, ben):-!.
translate(X, X). % catch-all clause for all words not to be translated

Alternatively, you could use maplist/3:

processWords(L,L2):-maplist(translate, L, L2).

translate(hello, bye):- !.
translate(simon, ben):- !.
translate(X, X). % catch-all clause for all words not to be translated

Upvotes: 3

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