forked from functionaljava/functionaljava
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathIntegers.java
More file actions
162 lines (143 loc) · 3.94 KB
/
Integers.java
File metadata and controls
162 lines (143 loc) · 3.94 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
package fj.function;
import fj.F;
import fj.F2;
import static fj.Function.curry;
import fj.Monoid;
import fj.data.List;
import fj.data.Option;
import static fj.data.Option.some;
import static fj.data.Option.none;
import static fj.Semigroup.intAdditionSemigroup;
import static fj.Semigroup.intMultiplicationSemigroup;
import static java.lang.Math.abs;
/**
* Curried functions over Integers.
*
* @version %build.number%
*/
public final class Integers {
private Integers() {
throw new UnsupportedOperationException();
}
/**
* Curried Integer addition.
*/
public static final F<Integer, F<Integer, Integer>> add = intAdditionSemigroup.sum();
/**
* Curried Integer multiplication.
*/
public static final F<Integer, F<Integer, Integer>> multiply = intMultiplicationSemigroup.sum();
/**
* Curried Integer subtraction.
*/
public static final F<Integer, F<Integer, Integer>> subtract = curry(new F2<Integer, Integer, Integer>() {
public Integer f(final Integer x, final Integer y) {
return x - y;
}
});
/**
* Negation.
*/
public static final F<Integer, Integer> negate = new F<Integer, Integer>() {
public Integer f(final Integer x) {
return x * -1;
}
};
/**
* Absolute value.
*/
public static final F<Integer, Integer> abs = new F<Integer, Integer>() {
public Integer f(final Integer x) {
return abs(x);
}
};
/**
* Remainder.
*/
public static final F<Integer, F<Integer, Integer>> remainder = curry(new F2<Integer, Integer, Integer>() {
public Integer f(final Integer a, final Integer b) {
return a % b;
}
});
/**
* Power.
*/
public static final F<Integer, F<Integer, Integer>> power = curry(new F2<Integer, Integer, Integer>() {
public Integer f(final Integer a, final Integer b) {
return (int) StrictMath.pow(a, b);
}
});
/**
* Evenness.
*/
public static final F<Integer, Boolean> even = new F<Integer, Boolean>() {
public Boolean f(final Integer i) {
return i % 2 == 0;
}
};
/**
* Sums a list of integers.
*
* @param ints A list of integers to sum.
* @return The sum of the integers in the list.
*/
public static int sum(final List<Integer> ints) {
return Monoid.intAdditionMonoid.sumLeft(ints);
}
/**
* Returns the product of a list of integers.
*
* @param ints A list of integers to multiply together.
* @return The product of the integers in the list.
*/
public static int product(final List<Integer> ints) {
return Monoid.intMultiplicationMonoid.sumLeft(ints);
}
/**
* A function that converts strings to integers.
*
* @return A function that converts strings to integers.
*/
public static F<String, Option<Integer>> fromString() {
return new F<String, Option<Integer>>() {
public Option<Integer> f(final String s) {
try { return some(Integer.valueOf(s)); }
catch (final NumberFormatException ignored) {
return none();
}
}
};
}
/**
* A function that returns true if the given integer is greater than zero.
*/
public static final F<Integer, Boolean> gtZero = new F<Integer, Boolean>() {
public Boolean f(final Integer i) {
return i > 0;
}
};
/**
* A function that returns true if the given integer is greater than or equal to zero.
*/
public static final F<Integer, Boolean> gteZero = new F<Integer, Boolean>() {
public Boolean f(final Integer i) {
return i >= 0;
}
};
/**
* A function that returns true if the given integer is less than zero.
*/
public static final F<Integer, Boolean> ltZero = new F<Integer, Boolean>() {
public Boolean f(final Integer i) {
return i < 0;
}
};
/**
* A function that returns true if the given integer is less than or equal to zero.
*/
public static final F<Integer, Boolean> lteZero = new F<Integer, Boolean>() {
public Boolean f(final Integer i) {
return i <= 0;
}
};
}