v2.0.1

README.md

@@ -70,6 +70,24 @@ The easiest way to precompile your JavaScript source code with embedded Constrai
 
 Functions ecapsulated in `${ ... }` are evaluated at rule application, as for JIT compilation too.
 
+## REPL
+
+CHR.js provides a REPL (Read-eval-print loop) to use it interactively with the command line. The `CHR >` REPL can be started by calling `node repl.js` from within the project's root directory. Then it is possible to directly define rules and call constraints:
+
+    CHR > dec(0) <=> true
+      [Rule] Added.
+    CHR > dec(N) ==> dec(N-1)
+      [Rule] Added.
+    CHR > dec(4)
+      ID  Constraint
+      --  ----------
+      1   dec(4)    
+      2   dec(3)    
+      3   dec(2)    
+      4   dec(1)
+
+The REPL can also be used programmatically by calling `var Repl = require('chr/repl')`.
+
 ## Background
 
 CHR.js was realized as a part of my Master Thesis in Computer Science at the University of Ulm, Germany. Its Project Report for a prototype implementation (versions `0.x`) with additional information about its architecture can be found online: https://fnogatz.github.io/paper-now-chrjs/.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "chr",
-  "version": "2.0.0",
+  "version": "2.0.1",
   "description": "Interpreter for Constraint Handling Rules (CHR) in JavaScript",
   "main": "src/index.js",
   "scripts": {

repl.js

@@ -22,7 +22,7 @@ function Repl () {
           var queries = parse(cmd.trim(), { startRule: 'Query' })
         } catch (e) {
           // no query
-          var res = eval(cmd)
+          var res = eval(cmd) // eslint-disable-line
           callback(null, res)
 
           return
@@ -39,15 +39,15 @@ function Repl () {
             if (query.original.slice(-1)[0] !== ')') {
               chrCmd += '()'
             }
-            var queryPromise = eval(chrCmd)
+            var queryPromise = eval(chrCmd) // eslint-disable-line
             return queryPromise
           })
         }, Promise.resolve())
 
         queryPromise.then(function () {
           clearInterval(spin)
           r.output.write(chr.Store.toString().split('\n').map(function (row) {
-            return '  '+row
+            return '  ' + row
           }).join('\n'))
           callback()
         }).catch(function (e) {
@@ -75,8 +75,12 @@ function errorMsg (e) {
 
   if (e.match(/^TypeError: chr\..* is not a function$/)) {
     var constraint = e.replace(/^TypeError: chr\.(.*) is not a function$/, '$1')
-    return 'Undefined constraint: '+constraint
+    return 'Undefined constraint: ' + constraint
   }
 
   return e
 }
+
+if (require.main === module) {
+  Repl()
+}

src/compile/head.js

@@ -286,10 +286,13 @@ Compiler.prototype.generateTellPromises = function generateTellPromises () {
       return
     }
 
+    var params
+    var lastParamName
+
     if (body.type === 'Replacement' && body.hasOwnProperty('num')) {
       // get parameters via dependency injection
-      var params = util.getFunctionParameters(self.replacements[body.num])
-      var lastParamName = util.getLastParamName(params)
+      params = util.getFunctionParameters(self.replacements[body.num])
+      lastParamName = util.getLastParamName(params)
 
       if (lastParamName && self.opts.defaultCallbackNames.indexOf(lastParamName) > -1) {
         // async
@@ -314,23 +317,23 @@ Compiler.prototype.generateTellPromises = function generateTellPromises () {
     }
 
     if (body.type === 'Replacement' && body.hasOwnProperty('func')) {
-      var func = eval(body.func)
-      var params = util.getFunctionParameters(func)
-      var lastParamName = util.getLastParamName(params, true)
+      var func = eval(body.func) // eslint-disable-line
+      params = util.getFunctionParameters(func)
+      lastParamName = util.getLastParamName(params, true)
 
       if (lastParamName && self.opts.defaultCallbackNames.indexOf(lastParamName) > -1) {
         // async
         parts.push(
           indent(1) + 'return new Promise(function (s) {',
-          indent(2) + '('+body.func+').apply(self, [' + util.replaceLastParam(params,'s') + '])',
+          indent(2) + '(' + body.func + ').apply(self, [' + util.replaceLastParam(params, 's') + '])',
           indent(1) + '})',
           '})'
         )
       } else {
         // sync
         parts.push(
           indent(1) + 'return new Promise(function (s) {',
-          indent(2) + '('+body.func+').apply(self, [' + params + '])',
+          indent(2) + '(' + body.func + ').apply(self, [' + params + '])',
           indent(2) + 's()',
           indent(1) + '})',
           '})'

src/compile/util.js

@@ -72,7 +72,7 @@ function getLastParamName (params) {
 }
 
 function replaceLastParam (params, replacement) {
-  return params.replace(/((^.*,|^)\s*)([^,]+)$/g, '$1'+replacement)
+  return params.replace(/((^.*,|^)\s*)([^,]+)$/g, '$1' + replacement)
 }
 
 function isArrowFunction (func) {