fixed bugs where I forgot to use new with constructors

environments.js

@@ -0,0 +1,50 @@
+/*
+ * An environment is just an object that maps identifiers to JLambda expressions
+ * with a few built-in (a standard Prelude environment)
+ */
+
+// returns the new environment after mutating it
+// values = [(identifier, JLambda expression)]
+
+var errors = require("./errors.js");
+var rep = require("./representation.js");
+
+
+function extend(env, values) {
+  for (var i = 0; i < values.length; i++) {
+    env[values[i][0].val] = values[i][1];
+  }
+  return env;
+}
+
+// creates a new environment initialized with the pairs in values
+function makeEnv(name, values) {
+  var env = {};
+  env.name = name;
+  for (var i = 0; i < values.length; i++) {
+    var name = values[i][0].val;
+    var val = values[i][1];
+    env[name] = val;
+  }
+  return env;
+}
+
+function lookup(name, env) {
+  var value = env[name];
+  if (!value) {
+    throw errors.UnboundError(name, env.name);
+  }
+  return value;
+}
+
+var prelude = makeEnv("prelude", [[new rep.Name("e"), new rep.FloatT(Math.E)],
+                                  [new rep.Name("pi"), new rep.FloatT(Math.PI)]]);
+
+var prelude_types = makeEnv("prelude_types",
+                            [[new rep.Name("e"), new rep.TypeOp("Float", [], false)],
+                            [new rep.Name("pi"), new rep.TypeOp("Float", [], false)]]);
+
+module.exports = { prelude : prelude,
+                   prelude_types : prelude_types,
+                   lookup : lookup,
+                   extend : extend };