3 files changed, 37 insertions, 24 deletions
diff --git a/src/genome/genome.js b/src/genome/genome.js
index 16de162..8e0c9f0 100644
--- a/src/genome/genome.js
+++ b/src/genome/genome.js
@@ -47,3 +47,5 @@ export function mutate(gene, type, value) {
       throw new Error(`unknown mutation type: '${type}'`);
   };
 }
+
+
diff --git a/src/mind/topology.js b/src/mind/topology.js
index 8e59c54..576ee83 100644
--- a/src/mind/topology.js
+++ b/src/mind/topology.js
@@ -1,5 +1,7 @@
 'use strict';
 
+import { create } from '../util';
+
 
 const DEFAULT_WEIGHT_MAX = 4;
 
@@ -18,12 +20,13 @@ const network_proto = {
 // create a new network
 export function network(input_count, internal_count, output_count, weight_max = 4) {
 	const count = input_count + internal_count + output_count;
-	const n = Object.create(network_proto);
-	n.input_count = input_count;
-	n.output_count = output_count;
-	n.adjacency = new Array(count).fill([]);
-	n.weight = [];
-	return Object.freeze(n);
+	const n = create({
+    input_count,
+    output_count,
+    adjacency: new Array(count).fill([]),
+    weight: [],
+  }, network_proto);
+	return n;
 }
 
 
@@ -53,24 +56,22 @@ function network_connect(n, source, sink, weight) {
 		throw new Error("attempt to use output as source");
 	}
 
-	const nn = Object.create(network_proto);
-	nn.input_count = n.input_count;
-	nn.output_count = n.output_count;
-	nn.adjacency = n.adjacency.map((row, i) => {
-		if (i === source && i === sink) {
-			// self-loop
-			return [...row, 2];
-		} else if (i === source) {
-			return [...row, 1];
-		} else if (i === sink) {
-			return [...row, -1];
-		} else {
-			return [...row, 0];
-		}
-	});
-	nn.weight = [...n.weight, weight];
-
-	return Object.freeze(nn);
+	return create({
+	  ...n,
+	  adjacency: n.adjacency.map((row, i) => {
+  		if (i === source && i === sink) {
+  			// self-loop
+  			return [...row, 2];
+  		} else if (i === source) {
+  			return [...row, 1];
+  		} else if (i === sink) {
+  			return [...row, -1];
+  		} else {
+  			return [...row, 0];
+  		}
+  	}),
+	  weight: [...n.weight, weight],
+	}, network_proto);
 }
 
 
diff --git a/src/util.js b/src/util.js
new file mode 100644
index 0000000..9f52551
--- /dev/null
+++ b/src/util.js
@@ -0,0 +1,10 @@
+'use strict';
+
+
+export function create(obj, proto=Object.prototype) {
+  const props = Object.keys(obj)
+    .map((key) => [ key, { value: obj[key], enumerable: true } ])
+    .reduce((acc, [ key, value ]) => ({ ...acc, [key]: value }), {});
+
+  return Object.create(proto, props);
+};