Illegal start of term in Prolog
I'm trying to write some predicates to solve the following task (learnprolognow.com)
Suppose we are given a knowledge base with the following facts:
tran(eins,one).
tran(zwei,two).
tran(drei,three).
tran(vier,four).
tran(fuenf,five).
tran(sechs,six).
tran(sieben,seven).
tran(acht,eight).
tran(neun,nine).
Write a predicate listtran(G,E) which translates a list of German number words to the corresponding list of English number words. For example:
listtran([eins,neun,zwei],X).
should give:
X = [one,nine,two].
I've written:
listtran(G,E):- G=[], E=[].
li开发者_如何学Gosttran(G,E):- G=[First|T], tran(First, Mean), listtran(T, Eng), E = [Mean|Eng).
But I get the error: "illegal start of term" when compiling. Any suggestions?
The last bracket in your last line should be a square one.
Also, you might want to make use of Prolog's pattern matching:
listtran([], []).
listtran([First|T], [Mean|EngT]):-
tran(First, Mean),
listtran(T, EngT).
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