How to get help on a Julia command on a Jupyter notebook?

New to Julia
1

I already tried :

?replace

ParseError:
# Error @ /home/onto/dev/projects/intro_julia.ipynb:1:1
?replace
╙ ── not a unary operator

Stacktrace:
 [1] top-level scope
   @ ~/dev/projects/intro_julia.ipynb:1

but it does work in the terminal…

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2

There is probably a better way, but you can do Base.Docs.doc("replace").

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3

You mean @docs replace ?

I did, and the output is very scary (because of some weird bug that’s not yet solved I guess, according to some comment I read on GH):

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ParseError: KaTeX parse error: No such environment: verbatim at position 7: \begin{̲v̲e̲r̲b̲a̲t̲i̲m̲}̲ String <: Abst…

EDIT: I found this as a workaround: Displaying docstrings in Notebook in VSCode (errors) - #4 by Paul_Soderlind

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4

Works for me in jupyter notebook:

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What notebook front-end are you using?

5

VSCode’s

6

? parses for me if I choose “Jupyter Kernel” (not “Julia release channel”) as the kernel source:

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A separate issue is that the front-end is trying to render the LaTeX version and failing.

The way the Jupyter protocol works is that the backend kernel (here, IJulia.jl) sends output as a dictionary in multiple formats, and the front-end chooses which one it wants to display. Here, IJulia sends text/plain, text/markdown, and text/latex formats for the documentation. The jupyter notebook is rendering the text/markdown format, but apparently VSCode is trying to render the text/latex format and failing. As noted above, you can force VSCode to use text/markdown via

display("text/markdown", Base.Docs.doc("replace"))

but this is a bit awkward. Another workaround is to tell Julia that Markdown.MD should never be displayed as text/latex:

import Markdown
Base.showable(::MIME"text/markdown", ::Markdown.MD) = false

at which point ?replace works:

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A longer-term “solution” would to patch IJulia.jl so that it never sends text/latex for Markdown.MD objects, but this is a bit annoying since the front-end is supposed to decide this.

The right thing would be for VSCode to fix this. They shouldn’t display as text/latex if text/markdown is available, since their text/latex display is apparently not fully functional. (However, their markdown rendering does not support LaTeX equations. So they really need to fix both.)

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7

Could this be fixed at the level of the vscode Julia extension? Or is it something that needs to be handled upstream, in vscode? In either case, is there a Github issue tracking this?

8

It would have to be handled upstream, in vscode. They have so far closed all of the related issues (linked in Cannot render Julia's help document in VScode Jupyter Notebook · Issue #13493 · microsoft/vscode-jupyter · GitHub), unfortunately.

It would be nice to at least file an issue for them to prefer text/markdown to text/latex when both are present in the display dictionary, since their support for the former is more full-featured. (Their text/latex support is basically limited to equations.) There doesn’t seem to be an issue that makes this clear.

But they don’t plan to support LaTeX equations in Markdown.

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