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First-class functions/Use numbers analogously: Difference between revisions
First-class functions/Use numbers analogously (view source)
Revision as of 15:26, 19 August 2010
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Line 107:
(#<FUNCTION ACOS> ∘ #<FUNCTION COS>)(0.5) = 0.5
(#<FUNCTION CUBE-ROOT> ∘ #<FUNCTION CUBE>)(0.5) = 0.5
=={{header|D}}==
<lang d>import std.stdio, std.algorithm;
void main() {
auto x = 2.0;
auto y = 4.0;
auto forward = [x, y, x + y ];
auto reverse = map!"1 / a"(forward);
auto multiplier = (double a, double b) {
return (double m){ return a * b * m; };
};
foreach(i, a; forward) {
auto b = reverse[i];
writeln("(", a ," * ", b, ")(0.5) = ", multiplier(a, b)(0.5));
}
}
</lang>
Output:
(2 * 0.5)(0.5) = 0.5
(4 * 0.25)(0.5) = 0.5
(6 * 0.166667)(0.5) = 0.5
<lang d>import std.stdio, std.math;
void main() {
auto forward = [(real x){ return sin(x); },
(real x){ return cos(x); },
(real x){ return x * x * x; }];
auto reverse = [(real x){ return asin(x); },
(real x){ return acos(x); },
(real x){ return x ^^ (1 / 3.0); }];
auto compose = (real delegate(real) a, real delegate(real) b) {
return (real x){ return a(b(x)); };
};
foreach(i, a; forward) {
writeln(compose(a, reverse[i])(0.5));
}
}
</lang>
Output:
0.5
0.5
0.5
=={{header|E}}==
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