Which versions of projects are loaded in the REPL?

[sungshik]

Scope (branches)

• Rascal: replace-lib-by-mvn-and-others (Replace lib:/// scheme by mvn:/// and file:/// and jar+file:/// everywhere rascal#1969)
• Rascal LSP: replace-lib-scheme (testing rascal without the lib scheme #454)

Problem

Situation

Suppose a REPL is created in project p (i.e., p is open in the workspace). The question is which version of p, and which version of any other project q, is loaded in the REPL for p. There are several options:

• Regarding the version of p:
  • If p ∉ {rascal, rascal-lsp}, then there is one option: the version of p in the workspace.
  • If p ∈ {rascal, rascal-lsp}, then there's a second option: the version of p in the VS Code extension.
• Regarding the version of q:
  • If q ∉ {rascal, rascal-lsp}, then there are three options:
    • no version of q;
    • the version of q in the workspace;
    • a version of q in the local Maven repository, when q is a dependency of p (declared in the POM of p).
  • If q ∈ {rascal, rascal-lsp}, then there's a fourth option: the version of q in the VS Code extension.

Expectation

• The version of p in the workspace is loaded in the REPL.
• The version of q is/isn't loaded in the REPL according to this table:

  q is a dependency of p	q is open in the workspace
  ☑️	☑️	the version of q in the workspace
  ☑️	🟪	a version of q in the local Maven repository
  🟪	☑️	no version of q†
  🟪	🟪	no version of q‡

  • † Exceptions: if q ∈ {rascal, rascal-lsp}, then
    • If q = rascal, then the version in the workspace is loaded.
    • If q = rascal-lsp, then the version in the VS Code extension is loaded.
  • ‡ Exceptions:
    • If q = rascal, then the version in the VS Code extension is loaded.
    • If q = rascal-lsp, then the version in the VS Code extension is loaded.

These expectations are based on the following underlying assumptions:

• If multiple projects are open in the workspace, then it matters in which project a REPL is created.
• If a project is open in the workspace, then it's impossible to load a different version of that project, because:
  • If a project is open, then it's under active development.
  • If a project is under active development, then the developer should observe the latest changes in the REPL.
  • (If a version in the local Maven repository should be loaded, then the project can be closed and/or (re)opened in another workspace.)
• Some versions of rascal and rascal-lsp are always loaded.

Actual

Currently (= in the branches listed above), there are several anomalous cases in which the actual version isn't the expected version. See the following issues for details:

• Rascal modules and Java classes of rascal are loaded from different versions #538
• Java classes of dependencies aren't loaded when they're open in the workspace #539
• rascal is loaded from the VS Code extension even if another version is depended on #540

Tasks

• Fix the anomalous cases
• Document which version a user should expect in which situation

Related work

• Stop shading rascal-lsp  #222
• Change how rascal-lsp is release on maven #288
• Finish separation of LSP interface from LSP implementation; move util::LanguageServer to standard library in rascal project #504