Falit.js

Static-typing and optional parameters in native JavaScript.

npm install falitjs

var falit = require('falitjs'),
    req = falit.required,
    opt = falit.optional,
    _ = require('underscore');
 
// configure falit settings
falit.settings({
    debug: true,
    throwErrors: false
})
 
// common usage pattern
var add = falit.binder(
        req.int, // a 
        req.int, // b
        function(a, b) {
        
            return a + b;
        });
 
add(5, 5)
 
// template usage pattern
var tmpl = falit.template(req.int, req.int, opt.func(console.log)),
 
    mul = tmpl.for(function(a, b, callback){ return callback(a * b)}),
    add = tmpl.for(function(a, b, callback){ return callback(a + b)});
 
var dbl = falit.binder(req.num, function(x){ return x * 2});
 
var add5 = _.partial(add, 5);
 
add(5, 5)
add(5, 5, add5)
mul(5, mul(5, 5, dbl))

Returns

10
10
15
250
[Finished in 0.0s]

todo

• unit tests (nodejs)
• remove underscore.js (underscorejs.org) dependency
• multiple, valid, types: falit.binder(oneOf(req.hex, req.posNum), ...)
• performance benchmarks
• ensure nodejs + webkit compatibility
• ensure crossbrowser compatibility

API

require('falitjs')

.binder([required parameters,] [optional parameters,] function)

Available Types

• any
• args
• array
• bool
• char
• date
• element
• finite
• float
• func
• hex
• int
• NaN
• negNum
• null
• num
• posNum
• obj
• regex
• str
• undefined

.optional.type[(defaultValue)]

.required.type[(validationFn)]

Used as place holder objects in .binder and .template

[opt|req].availableType will reserve the parameter slot for that given type.

falit.binder(required.int, required.obj, optional.func, ...)

Calling the placeholder will allow one of two things to happen:

• optional.availableType(..value of type..) will initiate a default value when omitted.
• required.availableType(req.func) will pass the supplied varable through a custom validation.

Example:

var add5 = falit.binder(opt.int(0), function(a){ return a + 5; });
 
>>> add5()
5
 
>>> add5(10)
15

Example:

var checkStr = function(s){ return s.length < 10; }
var shortString = falit.binder(req.str(checkStr), function(s){ console.log(s); })
 
>>> shortString('blake')
blake
 
>>> shortString('blake vandemerwe')
Failed validation,
  Supplied value did not pass
  Expected: [str], position: 0
 
null

Example:

var realExample = falit.binder(
        opt.int(0),
        opt.obj({debug: false}),
        req.func,
        function(delaySec, options, callback) {
            callback(null, [delaySec, options]);
        }
    )

>>> realExample(console.log)
null [ 0, { debug: false } ]

>>> realExample(10, console.log)
null [ 10, { debug: false } ]

>>> realExample({debug: true}, console.log)
null [ null, { debug: true } ]

The following fails, because the first argument doesn't match the first two optionals and then is validated against req.func.

>>> realExample(1.5, {debug: true}, console.log) 
 
Error: Invalid type,
  Expected: [func], position: 2
  Received: [any,finite,float,num,posNum], value: 1.5

Changing the realExample template to opt.any, opt.obj({debug: true}), req.func fails in the following example because the callback console.log was matched against opt.any and we're thrown an error that says we're missing a required argument.

>>> realExample(console.log)
 
Error: Missing required [func], in position: 1
 
           position: 1 --------v
>>> realExample(console.log, _____)
 
>>> realExample(console.log, console.log)
null [ [Function], { debug: true } ]
 
>>> realExample({}, {}, console.log)
null [ {}, {} ]
 

.settings(req.obj)

• debug, default: false
  • Determines whether debug messages should be printed to console or not.
• enabled, default: true
  • Enable type-checking; disabling is useful in production environment to reduce overhead.
• throwErrors, default: true
  • throw new Error on violation, when set to false execution integrity is unknown.

.template([required parameters,] [optional parameters])

.template(..) works like .binder(..) except that the last parameter is not treated as the function being bound to. Instead, you can construct a pattern of required and optional parameters that can be used in multiple instances for similar functions.

Example:

 
var twoInts = falit.template(req.int, req.int);
 
var add = twoInts.for(function(a, b){ return a + b; }),
    mul = twoInts.for(function(a, b){ return a * b; });
 
>>> add(5,5)
10
 
>>> mul(5,5)
25
 
>>> add('a', 5)
Invalid type,
  Expected: [int], position: 0
  Received: [any,char,str], value: a
 
>>> add(1.5, 1.5)
Invalid type,
  Expected: [int], position: 0
  Received: [any,finite,float,num,posNum], value: 1.5

.for(req.func)

Applies a required function to a template.

.whatIs(req.any)

Returns the meta-data associated with a given parameter. Useful for checking what types a known value will pass validation on.

Example:

>>> falit.whatIs([1,2,3])
{ posTypes: [ 'any', 'array' ], 
  bitMask: 5, 
  value: [ 1, 2, 3 ] }
 
>>> falit.whatIs(-1.5)
{ posTypes: [ 'any', 'finite', 'negNum', 'num' ],
  bitMask: 41089,
  value: -1.5 }
 
>>> falit.whatIs(undefined)
{ posTypes: [ 'any', 'undefined' ],
  bitMask: 1048577,
  value: undefined }
 
>>> falit.whatIs(Infinity)
{ posTypes: [ 'any', 'num', 'posNum' ],
  bitMask: 98305,
  value: Infinity }
 
>>> falit.whatIs(/\S+/)
{ posTypes: [ 'any', 'obj', 'regex' ],
  bitMask: 393217,
  value: /\S+/ }

Contributors

Blake VandeMerwe