Prolog 中的关联列表 [英] Associative Lists in Prolog

问题描述

我的任务是用列表实现地图.我们将关联列表定义如下:

my task is to implement maps with lists. We defined associative lists as follows:

[] 是列表，k 是键，v 是值，a 是关联列表，那么 [[k, v] |a] 是一个关联列表.

[] is the list, k is a key, v is a value and a is an associative list, then [[k, v] | a] is an associative list.

所以现在我必须编写一个谓词，在其中检查给定参数是否是关联列表.例如:

so now ive got to write a predicate, in which it checks if the given argument is a associative list. for example:

?- test([[a,5]]). -> true., ?- test([[1],[2]]). -> false.

我真的很绝望，我希望有人可以帮助我

im really in despair, i hope someone can help me there

问候

推荐答案

我可以说 关联列表被实现为 AVL 树，而不是点对列表，尽管后者是可能的.

I may say that associative lists in SWI-Prolog are implemented as an AVL-trees, not as the lists of a dotted pairs, though the latter is possible.

那么，让我们试试你的方法吧.

So, let's try your way.

[] 是列表，k 是键，v 是值，a 是关联列表，则 [[k, v] |a] 是一个关联列表.

[] is the list, k is a key, v is a value and a is an associative list, then [[k, v] | a] is an associative list.

一个更正:

我建议 [[ k |v ] |a] 更紧凑并且更具关联性")

I'd suggest [[ k | v ] | a] that is more compact and is "more associative" )

is_assoc([]).
is_assoc([[K|V] | AL]) :- %corrected 29 apr 2018 19:00 gmt+3
    !, is_assoc( AL ).


put(KV, AL, AL0) :-
   KV = [K|V],
   get(K, AL, V),
   remove(KV, AL, AL_KV),
   put(KV, AL_KV, AL0).

put(KV, AL, [KV | AL]).

get(K, AL, V):-
   member([K|V], AL).

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