BZLIB/SHP Web API & Converters

The previous post describes the basics on how to use the web API.  This post will focus on integrating your module with the web API.

As shown before, you can create a web API by creating an SHP script as follows:

;; /api/add2 
(:api-args (a number?) (b number?)) 
(+ a b) 

Where both a and b are validated as number?.  It would be nice if we can validate any type of scheme values, as long as the value can be created via the request input. 

For example - let's say that you have a struct with the following definition:

(define-struct foo (bar baz)) 

We want to do the following:

(:api-args (foo foo?)) ;; takes in the foo struct 

And let web API handle the rest.   This is achieved via converters.

Converters

The mappings between the request and the api args are done via converters, which maps the parameter key against the type's test function (such as number?).   And when you want to use the converter in the api-args expression, you specify the <test?> function in the parameter position in one of the following forms: