REPL hook-related issues

[topolarity]

I'm starting to use JL in the REPL via @mlechu's experimental JULIA_USE_FLISP_LOWERING=0 hook.

This is a catch-all issue to document any issues I encounter:

1. defining functions prints an anonymized name and seems to be the typeof(f) instead of f:

   julia> foo(x,y) = (x = y + y; x)
   #foo##0 (generic function with 1 method)
   
   julia> var"#foo##0"(1,2)
   ERROR: MethodError: no method matching var"#foo##0"(::Int64, ::Int64)
   
   julia> var"#foo##0".instance(1,2)
   4

2. const x = ... does not work:

   julia> const x = 3
   ┌ Info: JuliaLowering threw given input:
   │   code =
   │    quote
   │        $(Expr(:softscope, true))
   │        const x = 3
   │    end
   │   st0 =
   │    SyntaxTree with attributes kind,var_id,toplevel_pure,scope_type,name_val,syntax_flags,meta,scope_layer,value,is_toplevel_thunk,source
   │    [scope_block]                                                │ scope_type
   │      [const]                                                    │
   │        [=]                                                      │
   │          x                                  :: Identifier       │
   │          3                                  :: Integer          │
   │
   │   file = "REPL[7]"
   │   line = 1
   └   mod = Main
   ERROR: LoweringError:
   #= REPL[7]:1 =# - unsupported `const` declaration on local variable

3. non-global top-level assignments do not work:

   julia> y = 13
   13
   julia> y
   ERROR: UndefVarError: `y` not defined in `Main`
   Suggestion: check for spelling errors or missing imports.

[topolarity]

ParseErrors are also mangled pretty badly:

julia> global f = do x <enter>
┌ Info: JuliaLowering threw given input:
│   code = :($(Expr(:error, Base.Meta.ParseError("ParseError:\n# Error @ REPL[3]:1:12\nglobal f = do x\n#          └┘ ── invalid `do` syntax", Base.JuliaSyntax.ParseError(Base.JuliaSyntax.SourceFile("global f = do x", 0, "REPL[3]", 1, [1]), Base.JuliaSyntax.Diagnostic[Base.JuliaSyntax.Diagnostic(12, 13, :error, "invalid `do` syntax"), Base.JuliaSyntax.Diagnostic(14, 15, :error, "extra tokens after end of expression")], :none)))))
│   st0 =
│    SyntaxTree with attributes toplevel_pure,kind,value,var_id,name_val,syntax_flags,is_toplevel_thunk,meta,source,scope_layer
│    [error]                                                      │
│      Base.Meta.ParseError("ParseError:\n# Error @ REPL[3]:1:12\nglobal f = do x\n#          └┘ ── invalid `do` syntax", Base.JuliaSyntax.ParseError(Base.JuliaSyntax.SourceFile("global f = do x", 0, "REPL[3]", 1, [1]), Base.JuliaSyntax.Diagnostic[Base.JuliaSyntax.Diagnostic(12, 13, :error, "invalid `do` syntax"), Base.JuliaSyntax.Diagnostic(14, 15, :error, "extra tokens after end of expression")], :none)) :: Value │
│
│   file = "REPL"
│   line = 1
└   mod = Main
ERROR: LoweringError:
#= REPL:1 =# - Invalid syntax; K"error"

[mlechu]

Thanks for writing these down! I think they're all due to mishandling soft scopes.

@c42f For context, JULIA_USE_FLISP_LOWERING is a trivial patch to Base.jl to hook up JuliaLowering like we do for JuliaSyntax

+    # I've hard-coded the JuliaLowering and JuliaSyntax paths locally
     if get_bool_env("JULIA_USE_FLISP_PARSER", false) === false
         JuliaSyntax.enable_in_core!()
     end
+    if get_bool_env("JULIA_USE_FLISP_LOWERING", true) === false
+        JuliaLowering.activate!()
+    end

although these bugs should also reproduce with JuliaLowering.activate!() in the REPL.