问题描述
我怀疑 teyjus，λProlog 的主要实现，可能有点被遗弃，但 λProlog 是一个迷人的 Prolog，它应该让你使用高阶逻辑、假设推理和其他东西，这就是为什么我'我正在尝试使用它.
I suspect that teyjus, the main implementation of λProlog, might be a bit of abandonware, but λProlog is a fascinating Prolog that is supposed to let you use higher-order logic, hypothetical reasoning and other things, which is why I'm trying to use it.
文件example.sig":
File "example.sig":
sig example.
kind person, language type.
type hans person.
type german, french, italian language.
type grade person -> o.
type take person -> language -> o.
文件example.mod":
File "example.mod":
module example.
(grade P) :- (take P german), (take P french).
(grade P) :- (take P german), (take P italian).
take hans french.
然而，当我编译和加载它时，虽然它看起来可以工作，但假设的推理查询被拒绝:
However, when I compile and load it, while it appears to work, hypothetical reasoning queries get rejected:
[example] ?- take X Y.
The answer substitution:
Y = french
X = hans
More solutions (y/n)? y
no (more) solutions
[example] ?- grade X.
no (more) solutions
[example] ?- (take hans german) => (grade hans).
(1,19) : Error : Symbol => is not permitted within terms
我期待是"在那里结束.我做错了什么?
I was expecting a "yes" at the end there. What am I doing wrong?
推荐答案
Extend "example.sig"作者:
Extend "example.sig" by:
type whatif language -> o.
扩展example.mod"作者:
Extend "example.mod" by:
(whatif Q) :- ((take hans Q) => (grade hans)).
然后它就起作用了:
看起来 λProlog 是惰性软件，我提出了一个问题 #122.
或者有一些根本问题，它不起作用，
比如打字问题或编译器优化?
Looks like λProlog is lazyware, I raised an issue #122.
Or there are some fundamental problem that it doesn't work,
like typing problems or compiler optimizations?
P.S.:我活得很危险，从这里下载了 tjsim.exe 等:
http://www.eecs.ucf.edu/~leavens/Windows/usr-local-bin/
P.S.: I was living dangerously, and downloaded tjsim.exe etc.. from here:
http://www.eecs.ucf.edu/~leavens/Windows/usr-local-bin/
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