[Haskell-cafe] Well typed OS

Joachim Durchholz jo at durchholz.org
Fri Oct 5 21:09:13 UTC 2018

Am 05.10.2018 um 21:46 schrieb MarLinn:
> It seems when a Haskell projects gets a bit larger people tend to search 
> for ways to make it more modular. They try plugin frameworks, OS-level 
> dynamic linking, on-the-fly compilation etc. But I repeatedly get the 
> feeling that all these current approaches aren't actually very good. But 
> what if we had some kind of specialized format for compiled, dynamically 
> loadable, typed Haskell libraries? Something between a plain OS library 
> and bytecode. This might help make programs more modular while keeping 
> them type safe.

I've been believing that having a strict, universally-understood binary 
format was the one thing that enabled Java's library ecosystem. Which is 
huge, with a constant evolution of new generations and survival of the 

The downside is that compatibility with an established binary format is 
a pretty restricting design constraint on language evolution - you 
cannot evolve the language in ways that require a change to the binary 
format, unless you are willing to give up compatibility with all the 
precompiled binaries that are around.
I think it's doable, if the binary format has been carefully designed to 
allow the kind of extensions that are being tought about.

The other prerequisite is that if a change to the binary format is 
unavoidable, old formats stay readable. I.e. the loader needs to be able 
to read old format, indefinitely. Alternatively, code repositories could 
convert the code at upload time - the compatibility code would then live 
in the repositories and not in the loader (which makes the code harder 
to write but keeps the runtime smaller).

Well, that's what I can say from the Java and repository perspective.
I'm pretty sure there are other, and more important perspectives :-)


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