welcome to hell

//gcc 5.4.0
// Example with lambda  (needs --std=gnu99)
#include <stdio.h>


float l[]={ 3.141, 6.02, 42.0, 0.7 };

#define lambda(lambda$_ret, lambda$_args, lambda$_body) \
        ({                                              \
                lambda$_ret lambda$__anon$ lambda$_args \
                {return lambda$_body;}                  \
                        &lambda$__anon$;                \
        })

#define len(x) (sizeof(x)/sizeof(x[0]))

typedef void* auto_;

float apply(float (*fn)(float inp), float* l, int n)
{
        int i;
        float avg=0.0;
        printf("n=%i\n", n);
        for (i=0;i<n;i++)
        {
                avg+=fn(l[i]);
                printf("Running sum=%f\n", avg);
        }

        return avg/n;
}

int main(int argc, char *argv[])
{
        auto_ fn = lambda(float,(float x),2*x);

        printf("%f\n",apply(fn, l, len(l)));
        printf("%f\n",apply(lambda(float,(float x),2*x), l, len(l)));
        printf("%f\n",apply(lambda(float,(float x),x/3.0), l, len(l)));

        return 0;
}