43 lines
963 B
Objective-C
43 lines
963 B
Objective-C
#include <Foundation/Foundation.h>
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typedef id (^Function)(id);
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// a commodity for "encapsulating" double f(double)
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typedef double (*func_t)(double);
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Function encapsulate(func_t f) {
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return [[^(id x) { return [NSNumber numberWithDouble: f([x doubleValue])]; } copy] autorelease];
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}
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Function compose(Function a, Function b) {
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return [[^(id x) { return a(b(x)); } copy] autorelease];
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}
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// functions outside...
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double my_f(double x)
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{
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return x+1.0;
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}
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double my_g(double x)
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{
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return x*x;
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}
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int main()
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{
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NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
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Function f = encapsulate(my_f);
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Function g = encapsulate(my_g);
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Function composed = compose(f, g);
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printf("g(2.0) = %lf\n", [g([NSNumber numberWithDouble: 2.0]) doubleValue]);
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printf("f(2.0) = %lf\n", [f([NSNumber numberWithDouble: 2.0]) doubleValue]);
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printf("f(g(2.0)) = %lf\n", [composed([NSNumber numberWithDouble: 2.0]) doubleValue]);
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[pool release];
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return 0;
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}
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