Question

我正在练习在Prolog中使用DCG。我取一个像123这样的整数，将它“爆炸”成一个列表，即[1,2,3]，然后我想用DCG规则得到输出一到二三。到目前为止，我可以转换一个整数的列表，例如[1]成为一个但我不知道在列表中该做什么。我想尽可能多地使用DCG，因为这就是我练习的内容。这是我目前的代码：

tests( 1, [1] ).
tests( 2, [67] ).
tests( 3, [183] ).
tests( 4, [999] ).  

numToEng( N, Res ) :-
    tests( N, W ),
    print( 'test: ' ),print( W ),nl,
    explode( W, Exploded ),
    print( 'exploded: ' ),print( Exploded ),nl,
    phrase( num(Res), Exploded ).

explode( N, Explosion ) :-
    explode( N, [], Explosion ).
explode( 0, Explosion, Explosion ) :- !.    
explode( N, Inter, Explosion ) :- 
    Test is N mod 10, 
    NewN0 is  N - Test,
    NewN1 is NewN0//10, 
    explode( NewN1, [Test|Inter], Explosion ).

num( X ) --> digit( X ).    

digit(zero) --> [0].
digit(one) --> [1].
digit(two) --> [2].
digit(three) --> [3].
digit(four) --> [4].
digit(five) --> [5].
digit(six) --> [6].
digit(seven) --> [7].
digit(eight) --> [8].
digit(nine) --> [9].

我没有使用DCG的可能解决方案是我之前写过的，但我想知道如何使用DCG编写它。

% test cases, called by numToEng/2
tests( 1, [1] ).
tests( 2, [67] ).
tests( 3, [183] ).
tests( 4, [999] ).

% dictionary
digit(0,zero).
digit(1,one).
digit(2,two).
digit(3,three).
digit(4,four).
digit(5,five).
digit(6,six).
digit(7,seven).
digit(8,eight).
digit(9,nine).

% take an integer e.g. 123 and explode it
% into a list i.e. [1,2,3]
explode( N, Explosion ) :-
    explode( N, [], Explosion ).
explode( 0, Explosion, Explosion ) :- !.    
explode( N, Inter, Explosion ) :- 
    Test is N mod 10, 
    NewN0 is  N - Test,
    NewN1 is NewN0//10, 
    explode( NewN1, [Test|Inter], Explosion ).

% take a number in digits and convert it
% into english e.g. [1,2,3] would be
% [one,two,three]   
numToEng( N, Res ) :-
    tests( N, Test ),
    explode( Test, Exploded ),
    numToEng( N, Exploded, [], Res ).
numToEng( _, [], Rev, Res ) :-
    reverse( Rev, Res ).
numToEng( N, [H|T], Inter, Res ) :-
    digit( H, Word ),
    numToEng( N, T, [Word|Inter], Res ).

Answer 1

digits([]) --> [].
digits([D|Ds]) --> digit(D), digits(Ds).

示例：

?- explode(123,X), digits(Digits,X,[]).
X = [1, 2, 3],
Digits = [one, two, three]

Prolog：DCGS - 将数字转换为英语

1 个答案: