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tot

tot

Experimental language, superset of JavaScript, for writing async code like sync code.

Example

With tot you can call async functions like if they were sync. For exmaple you have the following funciton:

function something(message, callback) {
  setTimeout(function() {
    callback(null, 'hello '+message)
  }, 1)
}

Tot adds a new operator =: that lets you call this function like this:

var world =: something('world')

You can even declare multiple returning variables:

var foo, bar =: someFunction('world')

Full example

Full example (example.tot)

function something(message, callback) {
  setTimeout(function() {
    // if (message === 'bar') return callback(new Error('bar is not supported')) 
    callback(null, 'hello '+message)
  }, 1)
}
 
function done() {
  var args = Array.prototype.slice.call(arguments)
  console.log('Done')
  console.log(args.join('\n'))
}
 
exports.hello = function() {
  try {
    var foo =: something('foo')
    var bar =: something('bar')
    var baz =: something('baz')
 
    done(foo, bar, baz)
  } catch(e) {
    console.log('error', e.message)
  }
 
}

Usage

First init the npm module (install it with npm install tot --save)

require('tot')

Then you can require any .tot file.

require('./example').hello()

Benefits

  • Any async function can be used
  • You don't have to change the way you create async functions
  • It is simple as hell

How it works

Tot compiles to JavaScript. It converts this:

var foo =: something('foo')
var bar =: something('bar')

into this

something('foo', function(err, foo) {
  something('bar', function(err, foo) {
    
  })
})

And if you surround the code within a try - catch it also handles the error in every callback using the code you wrote in the catch block.

Things to have in mind

Tot is block-based

When using =: all the code from that operator to the end of the current block will be executed asynchronously (even though the syntax looks sync code). But anything outside the current block will be executed synchronously. For example:

if (condition) {
  var foo =: something('foo')
  console.log('world')
}
console.log('hello')

Tot generates the following code for this example:

if (condition) {
  something('foo', function(err, foo) {
    console.log('world')
  })
}
console.log('hello')

So console.log('hello') is always executed before console.log('world')

Arguments

The special arguments variable available in JavaScript when executing a function is also available but after any use of =: it will not match what you expect. If you want to use it, make a copy of it first:

// make a copy into an array 
var args = Array.prototype.slice.call(arguments)
var foo =: something('foo')
// do not use `arguments` here 

How it doesn't work

  • Tot does not create threads
  • Tot does not spawn processes

Sysntax highlighting in Sublime Text

Open a .tot file and go to the menu View → Syntax → Open all with current extension as... → JavaScript → JavaScript and all .tot files will be highlighted as JavaScript. Even though the =: does not exist in JavaScript the syntax highlighting will work pretty well.

Ignore intermediate js files

You can add *.tot.js in your .gitignore file to ignore intermediate js files generated by tot.

Drawbacks

Since Tot compiles to JavaScript any stack trace will reference lines of code of the generated JavaScript and not the original Tot code. This could be fixed using sourcemaps in a future.