circuithub / adt-typecheck.js

Type check your JavaScript data structures

adt-typecheck.js

Practical run-time type checking using adt.js.

Usage

adt.typecheck.js syntax is designed for CoffeeScript. It is certainly possible to use the library with JavaScript proper, however as an EDSL adt.typecheck is easiest to read using CoffeeScript shorthands. For this reason all of the examples here use CoffeeScript notation.

Two words of warning:

• Debugging wrapped up function calls can be painful. When debugging it is occasionally helpful to comment out the signature to avoid stepping through lots of this typechecking code.
• adt-typecheck.js is designed for flexibility rather than performance, especially since ADT's aren't natively implemented in JavaScript. If JavaScript performance is an issue for you, you may want to reconsider using a run-time typechecker.

Also, please note that adt-typecheck.js does not have an official release yet. Parts of the API can and will change over time.

Typecheck simple types

# TODO

Typecheck composite objects

# TODO

Typecheck arguments using function signatures

# TODO

Note that adt-typecheck.js will add some overhead to all of your functions signed in this way and is not appropriate for situations where high performance is required. This style of typechecking is probably more appropriate for server-side code than browser-side code (especially in situations where old and inefficient browsers need to be supported).

A proxy can be used in place of adt.typecheck.signature.function in production mode if performance is a concern. E.g.

if isDevelopmentMode
  fn = adt.typecheck.signature.function
else
  fn = (schema, f) -> f

Typecheck arguments to Node.js style chained functions

# TODO

The same proxy as the one for adt.typecheck.signature.function can be used in place of adt.typecheck.signature.chainFunction.

if isDevelopmentMode
  cfn = adt.typecheck.signature.chainFunction
else
  cfn = (schema, f) -> f

Typecheck your REST API's with an express middleware

The following snippet of code can be used to create a middleware for express that typechecks your incoming request body.

# TODO

Use it like this:

# TODO