Merge branch 'dev' of github.com:probmods/webppl into dev

docs/packages.rst

@@ -36,6 +36,18 @@ You can automatically prepend WebPPL files to your code by added a
       }
     }
 
+The use of some inference algorithms causes a caching transform to be
+applied to each ``wppl`` file. It is possible to skip the application
+of this transform on a per-file basis by placing the ``no caching``
+directive at the beginning of the file. For example::
+
+    'no caching';
+
+    // Rest of WebPPL program
+
+This is expected to be useful in only a limited number of cases and
+shouldn't be applied routinely.
+
 Macros
 ------
 

src/erp.js

@@ -26,6 +26,7 @@ var _ = require('underscore');
 var util = require('./util');
 var assert = require('assert');
 
+var LOG_PI = 1.1447298858494002;
 var LOG_2PI = 1.8378770664093453;
 
 function ERP(obj) {
@@ -227,6 +228,20 @@ var multivariateGaussianERP = new ERP({
   score: multivariateGaussianScore
 });
 
+var cauchyERP = new ERP({
+  sample: function(params) {
+    var location = params[0];
+    var scale = params[1];
+    var u = util.random();
+    return location + scale * Math.tan(180 * (u - 0.5));
+  },
+  score: function(params, x) {
+    var location = params[0];
+    var scale = params[1];
+    return -LOG_PI - Math.log(scale) - Math.log(1 + Math.pow((x - location) / scale, 2));
+  }
+});
+
 var discreteERP = new ERP({
   sample: function(params) {
     return multinomialSample(params[0]);
@@ -695,6 +710,7 @@ module.exports = setErpNames({
   gaussianERP: gaussianERP,
   multinomialSample: multinomialSample,
   multivariateGaussianERP: multivariateGaussianERP,
+  cauchyERP: cauchyERP,
   poissonERP: poissonERP,
   randomIntegerERP: randomIntegerERP,
   uniformERP: uniformERP,

src/header.wppl

@@ -1,3 +1,5 @@
+'no caching';
+
 // ERPs
 
 var flip = function(theta) {
@@ -25,6 +27,10 @@ var multivariateGaussian = function(mu, cov) {
   return sample(multivariateGaussianERP, [mu, cov]);
 };
 
+var cauchy = function(location, scale) {
+  return sample(cauchyERP, [location, scale]);
+};
+
 var uniform = function(a, b) {
   return sample(uniformERP, [a, b]);
 };

src/main.js

@@ -123,9 +123,8 @@ function parsePackageCode(packages, verbose) {
 }
 
 function applyCaching(asts) {
-  // This assume that asts[0] is the header.
-  return asts.map(function(ast, i) {
-    return i > 0 ? caching.transform(ast) : ast;
+  return asts.map(function(ast) {
+    return caching.hasNoCachingDirective(ast) ? ast : caching.transform(ast);
   });
 }
 

src/transforms/caching.js

@@ -80,7 +80,15 @@ function transformRequired(programAST) {
   return flag;
 }
 
+function hasNoCachingDirective(ast) {
+  return ast.body.length > 0 &&
+         ast.body[0].type === Syntax.ExpressionStatement &&
+         ast.body[0].expression.type === Syntax.Literal &&
+         ast.body[0].expression.value === 'no caching';
+}
+
 module.exports = {
   transform: cachingMain,
-  transformRequired: transformRequired
+  transformRequired: transformRequired,
+  hasNoCachingDirective: hasNoCachingDirective
 };

tests/test-caching.js

@@ -0,0 +1,33 @@
+'use strict';
+
+var _ = require('underscore');
+var parse = require('esprima').parse;
+var caching = require('../src/transforms/caching');
+
+var hasCachingDirectiveTests = {
+  test1: { code: "'no caching'", expected: true },
+  test2: { code: '"no caching";\n', expected: true },
+  test3: { code: '\n"no caching";\n1+1', expected: true },
+  test4: { code: '1 + 1', expected: false },
+  test5: { code: "1 + 1;\n'no caching'", expected: false },
+  test6: { code: '', expected: false }
+};
+
+var transformRequiredTests = {
+  test1: { code: 'IncrementalMH(model, 0);', expected: true },
+  test2: { code: 'Enumerate(model);', expected: false }
+};
+
+function generateTests(cases, testFn) {
+  return _.mapObject(cases, function(caseDef) {
+    return function(test) {
+      test.strictEqual(testFn(parse(caseDef.code)), caseDef.expected);
+      test.done();
+    };
+  });
+}
+
+module.exports = {
+  hasNoCachingDirective: generateTests(hasCachingDirectiveTests, caching.hasNoCachingDirective),
+  transformRequired: generateTests(transformRequiredTests, caching.transformRequired)
+};

tests/test-data/stochastic/expected/cauchy.json

@@ -0,0 +1,6 @@
+{
+  "hist": {
+    "true": 0.3743,
+    "false": 0.6257
+  }
+}

tests/test-data/stochastic/models/cauchy.wppl

@@ -0,0 +1,4 @@
+var model = function() {
+  var x = cauchy(2, 1.5);
+  return 1 < x && x <= 3;
+};

tests/test-inference.js

@@ -31,7 +31,8 @@ var tests = [
       beta: true,
       exponential: true,
       binomial: true,
-      poisson: true
+      poisson: true,
+      cauchy: true
     }
   },
   {