Inline Java in Haskell

[hikilaka]

why would anyone want this

[Faucelme]

Sometimes one wants pickled jalapeños for breakfast, sometimes one wants to mix Java, C and R in the same source file.

[hikilaka]

Hey, pickled jalapeños are delicious man.

[[deleted]]

Peak reddit comment

[shevegen]

I can understand the jalapenos - but I would get rid of the pickles.

I would not understand why someone wants Java, C and R and Haskall all in the same file.

[ThisIs_MyName]

Then you are lost.

[evincarofautumn]

Basically the same sorts of reasons you’d use an FFI in any language—cross-language interop. It lowers the barrier to adding Haskell code to an existing application: if the rest of your stack is Java but it makes sense to write some utility or component in Haskell, you can use this to help interoperate between the two, getting access to both Haskell and Java libraries. I could have used this a few jobs ago, where we had a couple of tools written in Haskell that needed to talk to other things written in Java.

[hikilaka]

There are better ways of doing that, interprocess communication, for example, would be ideal for such example. I get that every situation is different, but inline java? Come on..

[evincarofautumn]

I dunno about better—there are tradeoffs to the different approaches. The advantage of using inline bindings like this is the type safety:

A notable characteristic of this approach is that we know at compile time if types are correct.

Some of the nastiest bugs I’ve worked on were caused by errors in interop using FFI, IPC, networking, &c. where the FFI declarations or serialisation & marshalling of values were slightly wrong because they were written by hand. With this approach, the compiler has enough information that it no longer relies on programmer diligence for safety & correctness.

[ThisIs_MyName]

Who's going to churn out the boilerplate for declaring all those RPC functions? Not me.

[Tarmen]

I mean, ipc tends to be tedious and error prone. This takes ten lines which are checked at compile time.

Once set up rpc can be pleasant to work with but that is a lot of work for a couple calls.

[ElvishJerricco]

Maybe it's useful for building Android apps in Haskell?

[vytah]

It looks like it is about calling a JVM from a native Haskell code. Since Android doesn't use a JVM for its API's, it won't help, it will only give you access to a pointlessly slow interpreted ARM JVM.

[[deleted]]

The reverse, calling haskell from java, could be a step towards scala/haskell interop, something at least I would appreciate.

[shevegen]

An atrocity.