[Haskell-cafe] Web development work

Michael Snoyman michael at snoyman.com
Sat Sep 18 23:48:53 EDT 2010

On Sat, Sep 18, 2010 at 11:47 PM, Jeremy Shaw <jeremy at n-heptane.com> wrote:
> A RESTful API with JSON results sounds perfect. I will be surprised if the
> API useful for 3rd party sites happens to map on to the URL structure used
> by the main site. But if that works, all the better :)
> Of course, if your site which is creating the JSON is written in Haskell,
> and my site which is using it is written in Haskell, then it would be nice
> if I could somehow benefit from the haskell type checker telling me that you
> have changed your JSON a bit.
> In some small experimental RESTful-ish sites a I have made I tend to make
> the return values of the API be an algrebraic data type that all the API
> functions return. Then I have functions like SiteRetVal -> JSON, SiteRetVal
> -> XML, etc, which makes it easy to convert the output to whatever format
> the client wants. With a system like that, it is possible to have the
> SiteRetVal be in it's own hackage library. Your site and my site would both
> depend on that package. Then when you change the API return values, I get a
> new version of that library to type-check against... Not sure how
> valuable/feasible it is in practice though. I have only developed a
> prototype far enough to determine that it *can* be done. Whether it *should*
> be done remains to be seen.

There's one better: in addition to providing JSON output, I could
provide the output of the default Show typeclass (call the mimetype
x-text/haskell-show?), and then you can just use a readMay on your
end. Still using the intermediate package idea.

> Also, there maybe be some issues with using the accept header. In theory,
> you may someday provide XML (in addition to JSON). But I think that some
> browsers list xml has a higher preference than html. So then normal browser
> users will start getting xml instead of html?

I don't think any browsers list text/xml by default, rather
application/xhtml+xml, though I could be wrong.

> Anyway, the basic idea of a simple RESTful API with JSON is exactly what I
> was hoping for. The rest is implementation details, which I don't care much
> about as long as it works. I definitely do not want to turn this into a
> design by committee project.
> Also, once the site is 'done', it would be nice to hirer a graphic designer
> to give it a nice, clean, professional look.

Of course, if we want to make this an enterprise project, we would do
the graphic design by committee.

"I think blue is a nice color"
"Yes, but isn't that excluding the 50.23% of our target audience that's female?"
"Do women not like blue?"
"Let's take a vote, all in favor of women not liking blue?"
"OK, so as not be gender specific, we'll use a black background with
mauve text."

Sounds like a good idea to me.


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