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Previously, we were taking already hashed terms as input to the various intermediate compiler stages. We would then do things like lambda lifting, and hash the resulting definitions afterwards. However, this leads to problems like mutually recursive definitions that do not share a common hash. To rectify this, we instead do the intermediate operations on an _unhashed_ version of code looked up from the codebase. Essentially, we turn relevant definitions back into a letrec, do the floating, then hash the results of that processing. This gives proper hashes to the processed terms so that the compiled terms can be rehashed with relative ease. The system for this is unfortunately quite intricate. To get good decompiled output, we need to keep track of associations between original and floated terms _and_ floated and rehashed terms, then mediate between them in various places. |
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| scheme-libs/racket/unison | ||
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| unison-cli | ||
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| development.markdown | ||
| flake.lock | ||
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| hie.yaml | ||
| LICENSE | ||
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| unison | ||
| weeder.dhall | ||
The Unison language
Overview
Unison is a modern, statically-typed purely functional language with the ability to describe entire distributed systems using a single program. Here's an example of a distributed map-reduce implementation:
-- comments start with `--`
mapReduce loc fn ifEmpty reduce data = match split data with
Empty -> ifEmpty
One a -> fn a
Two left right ->
fl = forkAt loc '(mapReduce loc fn ifEmpty reduce !left)
fr = forkAt loc '(mapReduce loc fn ifEmpty reduce !right)
reduce (await fl) (await fr)
This function can be either simulated locally (possibly with faults injected for testing purposes), or run atop a distributed pool of compute. See this article for more in-depth coverage of how to build distributed computing libraries like this.
Other resources:
- Learn about the big idea behind Unison
- Check out the project website
- Say hello or lurk in the Slack chat
- Explore the Unison ecosystem
- Learn Unison
Building using Stack
If these instructions don't work for you or are incomplete, please file an issue.
The build uses Stack. If you don't already have it installed, follow the install instructions for your platform. (Hint: brew update && brew install stack)
If you have not set up the Haskell toolchain before and are trying to contribute to Unison on an M1 Mac, we have some tips specifically for you.
$ git clone https://github.com/unisonweb/unison.git
$ cd unison
$ stack --version # we'll want to know this version if you run into trouble
$ stack build --fast --test && stack exec unison
To run the Unison Local UI while building from source, you can use the /dev-ui-install.sh script. It will download the latest release of unison-local-ui and put it in the expected location for the unison executable created by stack build. When you start unison, you'll see a url where Unison Local UI is running.
See development.markdown for a list of build commands you'll likely use during development.
Language Server Protocol (LSP)
View Language Server setup instructions here.
Codebase Server
When ucm starts it starts a Codebase web server that is used by the
Unison Local UI. It selects a random
port and a unique token that must be used when starting the UI to correctly
connect to the server.
The port, host and token can all be configured by providing environment
variables when starting ucm: UCM_PORT, UCM_HOST, and UCM_TOKEN.
Configuration
See the documentation for configuration here