Hacker News Reader

Comment by noelwelsh | Hacker News Reader

Many people, including experienced Scala developers (e.g. me), find Dispatch hard to use. The BlueEyes HTTP Client is much simpler:

   val client = new HttpClientXLightWeb
   client.host("somesite.com").get[ByteChunk]("/some/url")

That, plus some imports, is all you need

View on HN

It's been a long time since I touched Scala — and I never used it for web stuff at the time anyway — but is this really typical?

It's mostly an absurd comparison (equivalent to Fibonacci or something), and a tangent besides, but in Clojure:

    (slurp "http://somesite.com/some/url")

That gives me the response as a string. If I want a binary stream:

    (clojure.java.io/input-stream "http://somesite.com/some/url")

The same functions work for URLs, URIs, Files, and strings that describe them.

Do you think the code is hard to read?

BlueEyes is a framework for writing high performance web services. For it's use cases you care whether you're getting or putting. Thus it is explicit. Similarly, you care about performance, and so don't want to parse strings if you can help it -- thus you set the host once rather than parsing a URL.

For a pure ease-of-use library Dispatch is probably the best, if you can figure out the syntax (see earlier discussion). In Dispatch you can write something like

  url("http://somesite.com/some/url") >>> System.out

I forget how you read into a string. Probably change >>> to >>@!#$$T%^@#$% or similar.

No, I don't take (much) issue with your example's readability, I just thought you were offering a typical snippet for the easy path for "I need to perform a GET".

Of course, more involved interactions require an API with more knobs. Clojure has a number of options, including touching the JDK's HTTP client API, or using a wrapper around something more grounded like clj-http[1] / Apache HTTPComponents.

[1] https://github.com/dakrone/clj-http

Dispatch is so often used as an example of hard to read Scala code/operator overloading abuse, that I think it should be shuttered just for the greater good of the Scala community.

That being said, programmers can over-engineer things in any language; it's just that in Java, over-engineered things are "incomprehensible and huge" while in Scala over-engineering things are usually "incomprehensible and small".

Thanks. I ended up using scalaj-http, which was much simpler. But it took me a few days to find it. Dispatch does very well SEO-wise for Scala HTTP. The only other option I had come across was using http-client.

Have any good recommendations for JSON parsers? This was another case where I found the common libraries to be rather obtuse.

I use BlueEyes here (I'm a big fan of BlueEyes). It's JSON library is based on Lift-JSON. Lift-JSON is fairly commonly used, so perhaps you've run across it already. It's actually fairly simple to use and is one of the few parts of Lift that has decent documentation:

https://github.com/lift/lift/tree/master/framework/lift-base...

Here's a summary:

The JSON AST is pretty straightforward. The JSON DSL works like this:

- A tuple ("key", value) constructs a key/value pair

- ~ joins them together to construct an object

E.g. ("foo", 1) ~ ("bar", "Hi") = {"foo": 1, "bar": "Hi"}

I never actually invoke the parser myself. BlueEyes does it if you change the ByteChunk is my example above to JValue.

Drop me an email (noel at untyped dot com) or tweet (@noelwelsh) or IM or Skype or whatever if you want to discuss more.

Alternatively, I've never used Coda Hale's Jerkson package, but I expect it is of high quality.

I don't use lift-the-web-framework, but after looking around at the scala json options, decided on and am so far really liking lift-json's package.

Does any of raw string <-> JSON AST, or maps/lists <-> JSON (...IIRC), or case objects <-> JSON (what I'm using it for, pseudo ORM).

Or just do a:

  val source = scala.io.Source.fromURL("http://news.ycombinator.com/item?id=3264849")

Reply on news.ycombinator.com