vscode-ghc-simple new bios design

new-bios.md

A bit of extra stuff

• TODO Make on-configuration-change restart more specific
• TODO Alert users for configuration migration
  • ghcSimple.useObjectCode is gone.
  • ghcSimple.workspaceType is gone.

Considerations not mentioned

• Configuration options?
  • Preferably minimal, delegate most to hie.yaml or .ghcid
  • Let the user override the detection mechanism?
• startupCommands

GHCi session sharing

• Implicit sharing
• Documents each get their own configuration
• Two documents can share one GHCi instance
  • If the configurations are sharable (flag), and the key field is the same
• The key is a JSON serializable field emitted along with the configuration
  • Informaation like 'This is a stack project on /path/to/root with component foo'

External extension access to GHCi

• TextDocument → Session: Same Session for. Suitable for calling one-off commands.
• Configuration → Session: More flexible, sharing still possible
  • Specify a 'generic' key → Shared across all extensions
  • Specify an extension-specific key (maybe extensionId in key) → Shared within one extension only
  • ... Other use cases?
  • Can also specify non-sharable session
• Probably also access to configuration detection algorithm.

Dependency

• Each configuration can specify a set of glob patterns
• If any of these fiels are changed, the configuration's session is killed
• Dependency of shared sessions is the union of

New detection logic:

Legends:

• (TODO): I know how this works, but I didn't write the code yet
• (???): I still need to figure out how this works

For each file, considered separately:

• If file has no workspace
  • If stack runnable, file-stack
  • Else, file
• Else, If workspace has custom command
  • If replScope is workspace, custom-workspace
  • Else: custom-file
• Else, if hie.yaml in workspace root:
  • This is a hie-bios-cradle workspace
  • Find Cradle match in hie.yaml (TODO)
  • Find GHCi command like hie-bios (???)
  • Find deps like hie-bios (???)
• Else, if .ghcid in workspace root
  • This is a ghcid workspace
  • Start GHCi using specified commands (TODO)
  • Deps as specified (TODO)
• Else, if stack.yaml in workspace root:
  • stack query to get targets (TODO)
  • stack repl $target (TODO)
  • Deps (???)
• Else, if *.cabal or cabal.project or cabal.project.local in workspace root:
  • cabal v2-repl all (TODO)
  • Deps (???)

Example hie.yaml

cradle:
  cabal: # Or stack
  - path: "./src"
    component: "lib:hie-bios" # cabal v2-repl lib:hie-bios
  - path: "./test"
    component: "test:bios-tests" # cabal v2-repl test:bios-tests

  cabal:
    component: "lib:hie-bios" # cabal v2-repl lib:hie-bios
  stack:
    component: "hie-bios:lib" # stack repl hie-bios:lib
  bios:
    program: "program to run"
    dependency-program: "optional program to run"
  direct:
    arguments: ["list","of","ghc","arguments"]
  none: # Maybe just fail. Cache the result
  multi: - path: ./
           config: { cradle: ... }

dependencies:
  - someDep

Example .ghcid

(From GHC)

--command sh ./hadrian/ghci
--reload compiler
--reload ghc
--reload includes
--restart hadrian/

This command is unquoted???

How does ghcid really parse these?