* Rewriting Dhall.LSP.Backend.Dhall: Implement new API
The old "backend" consisted of a random collection of ways to invoke
Dhall:
- runDhall :: FilePath -> Text -> IO (Expr Src X)
- runDhallSafe :: FilePath -> Text -> IO (Maybe (Expr Src X))
- loadDhallExprSafe :: FilePath -> Text -> IO (Maybe (Expr Src X))
The new backend exposes a slightly more though-out API. This also lays
the foundation for performance improvements in the dhall lsp server via
caching.
* Reorder code in Dhall.LSP.Backend.Dhall
* Remove unused constructor
* Rewrite and document Backend.Formatting
* Refactor Dhall.LSP.Backend.Linting
* Refactor Dhall.LSP.Backend.ToJSON
* Adapt Diagnostics backend to the new Dhall API
* Remove old Dhall backend API
* Implement caching; revamp LSP frontend
This commit implements caching of Dhall expressions: we only need to
fetch, typecheck and normalise each import once per session, unless they
change! This means that `dhall-lsp-server` is now viable for non-trivial
Dhall projects, for example probing around in `dhall-nethack` everything
feels near-instantaneous once the imports have been resolved.
This implementation currently has a bug: we don't invalidate imports
transitively, i.e. if A.dhall loads B.dhall and B.dhall changes we do
not discard the cached version of A.dhall. This should be reasonably
easy to fix given some time with Dhall's import graph. Furthermore,
there is some cleaning up left to do:
- Fix warnings
- Reorganise things in a less ad-hoc way
- Make the code a bit prettier
* Fix caching of errors
* Use `bimap` instead of `first` and `second`
* Re-export `Dhall.lint` rather than aliasing
Rids us of some boilderplate
* Use MVar instead of TVar for server state
The main benefit is that we get to use `modifyMVar_` which does updating
of the shared state for us (and gracefully handles any uncaught
exceptions).
* Don't invalidate hashed imports
Fixes a misinterpretation on my end of the correct behaviour regarding
the caching of imports. Quoting @Gabriel439:
> A hashed import is valid indefinitely once it is successfully
> resolved, even when the underlying import later becomes broken. That's
> why missing sha256:… works so long as the cache has that import cached
> (and this behavior is part of the standard).
* Cleanup Dhall.LSP.Backend.Dhall a little bit
* Add note about fixing cache invalidation
* Use TemplateHaskell to generate state lenses
* Make types of `typeAt` and `annotateLet` more expressive
Both assume the input to be well-typed; by using `WellTyped` rather than
`Expr Src X` as the type of their input we can make this explicit.
This change exposed a bug (also fixed in this commit) in the
type-on-hover functionality: we run `typeAt` only if the input was
well-typed _the last time we checked it_ (which was at the last save);
this means that if the code changed without being written to disk we
would happily try to normalise (in `typeAt`) non-well-typed code...
* Fix type of typecheck
Typecheck returned the well-typed _type_ of a given expression, while I
was assuming it would certify the input to be well-typed. Silly indeed.
* Remove `checkDhall` from Dhall.Backend.Diagnostics
Removes the left-over stub from the change to the new Dhall backend.
* Update comments and remove TODO note
* Remove superfluous parentheses
* Simplify MonadState code via lens combinators
* Use `guard` instead of matching on True
* Remove more superfluous parentheses
At the moment the VSCode plugin contains a hacked-together prototype of
a dhall-to-json (and -to-yaml) preview feature. We should ultimately
move that kind of functionality to dhall-lsp-server to 1) minimise the
amount of VSCode specific code and 2) avoid having to work with and fix
bugs in typescript code ;)
This commit takes us most of the way there; what is missing is the
ability to create files (via a WorkspaceEditRequest), which is not yet
implemented by haskell-lsp-types. I will wait with exposing the
corresponding command (and removing the existing preview code) in
vscode-dhall-lsp-server until this is fixed upstream.
* Clean up dhall-lsp-server's Main.hs
Also adds haddock comments.
* Remove TODO comment
The comment talks about adding a mechanism for protocol-level logging to
dhall-lsp-server. Since the VSCode LSP implementation has this feature
already baked in on the client side, we don't have to implement it
ourselves.
* Simplify dhall-lsp-server's infrastructure
So far we had a system where we set up the LSP message handlers to relay
messages to a separate dispatcher thread via a shared channel. Since our
language server is at the same time designed in a completely synchronous
manner, this complication turns out to be unnecessary.
* Remove sample code
* Fix unused variable warning
* Reorganise dhall-lsp-server's module hierarchy
Prefixes all modules with "Dhall.LSP.".
Previously:
Backend.Dhall.
.Diagnostics
.Formatting
LSP.
.Handlers
.Handlers.
.Diagnostics
.DocumentFormatting
.Server
Now:
Dhall.LSP.
.Backend.
.Diagnostics
.Formatting
.Handlers
.Handlers.
.Diagnostics
.DocumentFormatting
.Server
* Make dhall-lsp-server tests compile again
They still fail though!
