Re: [Haskell-cafe] Glasgow Distributed Haskell

Paul Johnson пишет:

Joel Reymont wrote:

...

I'm after Erlang in Haskell, if you will, for fault-tolerance and scalability.

I think the way to do Erlang in Haskell is to build a middleware layer on top of the language, not try to make the language into something it is not. In this kind of environment you need to be able to upgrade components while the system is running. The careful Haskell habit of separating stateful operations from pure functions is useful here. I gather that the HAppS project is working along similar lines, and for similar reasons. Take a look at it.

I think I should point you to: http://www.cs.umd.edu/~mwh/papers/neamtiu06dsu.html --------------------------------------------------------------- *Practical Dynamic Software Updating for C*. Iulian Neamtiu, Michael Hicks, Gareth Stoyle, and Manuel Oriol. In /Proceedings of the ACM Conference on Programming Language Design and Implementation (PLDI)/, pages 72-83, June 2006. Software updates typically require stopping and restarting an application, but many systems cannot afford to halt service, or would prefer not to. /Dynamic software updating/ (DSU) addresses this difficulty by permitting programs to be updated while they run. DSU is appealing compared to other approaches for on-line upgrades because it is quite general and requires no redundant hardware. The challenge is in making DSU /practical/: it should be flexible, and yet safe, efficient, and easy to use. In this paper, we present Ginseng, a DSU implementation for C that aims to meet this challenge. We compile programs specially so that they can be dynamically patched, and generate most of a dynamic patch automatically. Ginseng performs a series of analyses that when combined with some simple runtime support ensure that an update will not violate type-safety while guaranteeing that data is kept up-to-date. We have used Ginseng to construct and dynamically apply patches to three substantial open-source server programs-/Very Secure FTP daemon/, /OpenSSH sshd daemon/, and /GNU Zebra/. In total, we dynamically patched each program with three years' worth of releases. Though the programs changed substantially, the majority of updates were easy to generate. Performance experiments show that all patches could be applied in less than 5 /ms/, and that the overhead on application throughput due to updating support ranged from 0 to at most 32%. --------------------------------------------------------------- So, it is not completely impossible for haskell being updated on-the-fly.