Potential conflict with Pluto?

[max-sixty]

I'm new to Julia and so I might be making a naive mistake.

In Pluto, running something like this prints the docs! This may be because in pluto, the docs are offered in a pop-up on the bottom right.

@chain begin "3,4,3,1,2"
	strip
end

and running

@chain begin "3,4,3,1,2"
	strip
	split(",") 
end

returns an error

MethodError: no method matching split(::Base.Docs.Binding, ::String)

Closest candidates are:

split(!Matched::T, ::Any; limit, keepempty) where T<:AbstractString at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/base/strings/util.jl:417

    top-level scope@Local: 3[inlined]

It's not purely a Pluto issue though — @_ from Underscores.jl doesn't have this problem, maybe because it doesn't use multiple lines?

Thank you!

[max-sixty]

FWIW surrounding the block with another begin ... end makes it work, so possibly this is more of a Pluto issue?

[jkrumbiegel]

Hah I remember seeing this error once and not understanding it, but now I do. The problem is that the string "3,4,3,1,2" above strip is parsed into a docstring for the strip function. This happens at parse time and I can't do anything about it in my macro. You can see this if you look at the output of Meta.@dump:

julia> Meta.@dump @chain begin
               "3,4,3,1,2"
               strip
               split(",") 
       end
Expr
  head: Symbol macrocall
  args: Array{Any}((3,))
    1: Symbol @chain
    2: LineNumberNode
      line: Int64 1
      file: Symbol REPL[5]
    3: Expr
      head: Symbol block
      args: Array{Any}((4,))
        1: LineNumberNode
          line: Int64 2
          file: Symbol REPL[5]
        2: Expr
          head: Symbol macrocall
          args: Array{Any}((4,))
            1: GlobalRef
              mod: Module Core
              name: Symbol @doc
            2: LineNumberNode
              line: Int64 2
              file: Symbol REPL[5]
            3: String "3,4,3,1,2"
            4: Symbol strip
        3: LineNumberNode
          line: Int64 4
          file: Symbol REPL[5]
        4: Expr
          head: Symbol call
          args: Array{Any}((2,))
            1: Symbol split
            2: String ","

Of course, now that I think about it, I could specifically intercept this situation and re-expand the doc macro call into a string and a function..

[jkrumbiegel]

The workaround is to put the string before the begin block to avoid the doc parsing

[max-sixty]

Thanks @jkrumbiegel! I'm less familiar with how this works — should I put an issue in Pluto? Or is this unavoidable on their side too?

[jkrumbiegel]

No they're just expanding the macro and finding the docstring, I could try to fix that, remove the doc string in the first line if there's one

[jkrumbiegel]

Fixed in #41