feat: add much faster time to botec example, using parallelism

examples/more/12_time_to_botec_parallel/example.c

@@ -0,0 +1,33 @@
+#include "../../../squiggle.h"
+#include "../../../squiggle_more.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main()
+{
+    double p_a = 0.8;
+    double p_b = 0.5;
+    double p_c = p_a * p_b;
+
+    double sample_0(uint64_t* seed){ return 0; }
+    double sample_1(uint64_t* seed) { return 1; } 
+    double sample_few(uint64_t* seed) { return sample_to(1, 3, seed); } 
+    double sample_many(uint64_t* seed) { return sample_to(2, 10, seed); } 
+
+    int n_dists = 4;
+    double weights[] = { 1 - p_c, p_c / 2, p_c / 4, p_c / 4 };
+    double (*samplers[])(uint64_t*) = { sample_0, sample_1, sample_few, sample_many };
+    double sampler_result(uint64_t* seed) { 
+        return sample_mixture(samplers, weights, n_dists, seed);
+    } 
+
+    int n_samples = 1000 * 1000; 
+    int n_threads = 16;
+    double* results = malloc(n_samples * sizeof(double));
+    parallel_sampler(sampler_result, results, n_threads, n_samples);
+
+    double avg = array_sum(results, n_samples)/n_samples;
+    printf("Avg: %f", avg);
+    free(results);
+}