int (^ myBlock)(int) = ^ (int num) { return num * multiplier; };

int d = i % 10;
repeat(10, ^ { putc ('0'+d); });


void (^ block)(void);
typedef void (^ vstr_t)(char *);
typedef void (^ workBlk_t)(void);

void AllLinesInFile(char *f, vstr_t block) {
    FILE *fp = fopen(f, "r");
    if (!fp) return;
    char line[1024];
    while (fgets(line, 1024, fp))
        block(line);
    fclose(fp);
}


@implementation NSArray (WWDC)
- (NSArray *)map:(id (^ )(id))xform {
    id result = [NSMutableArray array];
    for (id elem in self)
        [result addObject:xform(elem)];
    return result;
}

- (NSArray *)collect:(BOOL ( ^ )(id))predicate {
    id result = [NSMutableArray array];
    for (id elem in self)
        if (predicate(elem))
            [result addObject:elem];
    return result;
}

// corner case: block literal in use with return type
id longLines = [allLines collect: ^ BOOL (id item) {
                    return [item length] > 20;
                }];

// corner case: block literal in use with return type
id longLines = [allLines collect: ^ BOOL* (id item) {
                    return [item length] > 20;
                }];

@end

// 1. block literal: ^{ ... };
// 2. block declaration: return_t (^name) (int arg1, int arg2, ...) NB: return_t is optional and name is also optional
// 3. block inline call ^ return_t (int arg) { ... }; NB: return_t is optional