Merge pull request #871 from null-a/unary-plus

Fix unary plus

src/ad.js

@@ -53,7 +53,11 @@ ad.scalar.logGamma = ad.newUnaryFunction({
 });
 
 ad.scalar.plus = function(x) {
-  return ad.scalar.add(0, x);
+  if (ad.isLifted(x) && typeof ad.value(x) === 'number') {
+    return x;
+  } else {
+    return +x;
+  }
 };
 
 // HACK: Used to access Tensor in daipp.

tests/test-data/deterministic/expected/scalar.json

@@ -0,0 +1,3 @@
+{
+  "result": true
+}

tests/test-data/deterministic/models/scalar.wppl

@@ -0,0 +1,18 @@
+all(idF, [
+  (function() {
+    return 2 + 2 === 4;
+  })(),
+
+  (function() {
+    return +1 === 1;
+  })(),
+
+  (function() {
+    var x = ad.lift(1);
+    return +x === x;
+  })(),
+
+  (function() {
+    return +'1' === 1;
+  })()
+]);