13 |
15 | Yield Prolog
16 | Download
17 |
18 | Documentation
20 |
21 | Query Editor
22 |
23 | Benchmarks
24 |
25 | Report
27 | Bugs
28 |
29 | Sourceforge
30 | Project
31 |
32 | 
35 | |
36 | Yield
37 | Prolog lets you embed
38 | Prolog programs directly in Python, C# [1]
39 | or Javascript [2]
40 | by using the yield
41 | keyword. For example,
42 | here is the classic "uncle" predicate in Prolog:
43 |
44 |
46 |
47 |
48 |
49 | uncle(Person, Uncle) :-
parent(Person, Parent),
brother(Parent, Uncle).
50 | |
51 |
52 |
53 |
54 |
55 | (This says that a person has an uncle if the person has a parent and
56 | that
57 | parent has a brother.) And here it is in Yield Prolog:
58 |
59 |
61 |
62 |
63 | Python
65 | |
66 | C#
68 | |
69 |
70 |
71 |
72 | def uncle(Person, Uncle):
Parent = Variable()
for l1 in parent(Person, Parent):
for l2 in brother(Parent, Uncle):
yield False
73 | |
74 |
75 | IEnumerable<bool> uncle(object Person, object Uncle) {
Variable Parent = new Variable();
foreach (bool l1 in parent(Person, Parent)) {
foreach (bool l2 in brother(Parent, Uncle))
yield return false;
}
}
76 | |
77 |
78 |
79 | | Javascript |
80 |
81 |
82 |
83 | function uncle(Person, Uncle) {
var Parent = new Variable();
for each (var l1 in parent(Person, Parent)) {
for each (var l2 in brother(Parent, Uncle))
yield false;
}
}
84 | |
85 |
86 |
87 |
88 |
89 | As you can see, the flow of the code in Yield Prolog is similar to
90 | Prolog. The Tutorial explains how
91 | these
92 | examples work, without expecting you to know Prolog. And the benchmarks show that Yield Prolog in C# can
94 | be faster than efficient Prolog systems like Yap Prolog and XSB.
95 |
96 | Yield Prolog is made possible by the yield keyword, which
98 | automatically creates iterators that you can nest, combined with Yield
99 | Prolog's Variable class
100 | which can unify a variable with other values (just like in
101 | Prolog). There is no "API" standing between your code and Yield Prolog,
102 | because
103 | you just use the yield
104 | keyword to make "iterator functions" wherever you need them. Yield
105 | Prolog is part of your code, which can mix Prolog-style predicates
106 | directly with ordinary arrays, file I/O, GUI calls and all your own
107 | classes. Because it lets you mix these, Yield Prolog unifies the declarative
109 | and procedural
110 | programming models.
111 |
112 |
1.
113 | Tested
114 | with
115 | C#
116 | .NET 2008 and Mono 2.0.
117 | 2.
119 | Yield Prolog for Javascript is supported in Firefox 3 and Seamonkey 2,
122 | which fully supports the yield
123 | keyword in EcmaScript 3.1.
124 | |
125 |
126 |