Becasuse of GitHub I am not that used to thinking of git as a peer to peer decentralised version control system - despite the fact I know this theoretically. An upshot of this property that any folder that you have access to can act as a remote.

This came in handy today, rigging up a way to deploy code to a server that has very limited connectivity to the outside world.

First I copied my local copy over to the server.

Then on my workstation I added the folder as a remote:

git remote add prod \\analytics\blah\project_name

Then I can fetch that remote to get the branch metadata:

git fetch prod

after which I can push to it

git push prod

Well sort of. Initally I got this error:

git push prod
Enumerating objects: 18, done.
Counting objects: 100% (18/18), done.
Delta compression using up to 8 threads
Compressing objects: 100% (10/10), done.
Writing objects: 100% (11/11), 1.37 KiB | 467.00 KiB/s, done.
Total 11 (delta 6), reused 0 (delta 0), pack-reused 0
remote: Checking connectivity: 11, done.
remote: error: refusing to update checked out branch: refs/heads/main
remote: error: By default, updating the current branch in a non-bare repository     
remote: is denied, because it will make the index and work tree inconsistent        
remote: with what you pushed, and will require 'git reset --hard' to match
remote: the work tree to HEAD.
remote:
remote: You can set the 'receive.denyCurrentBranch' configuration variable
remote: to 'ignore' or 'warn' in the remote repository to allow pushing into        
remote: its current branch; however, this is not recommended unless you
remote: arranged to update its work tree to match what you pushed in some
remote: other way.
remote:
remote: To squelch this message and still keep the default behaviour, set
remote: 'receive.denyCurrentBranch' configuration variable to 'refuse'.
To \\analytics\blah\project_name
 ! [remote rejected] main -> main (branch is currently checked out)
error: failed to push some refs to '\\analytics\blah\project_name

Git refused to accept my commits. The issue it is warning me about is that if I did push commits onto the main branch, the HEAD pointer in the copy on the server is not updated. So it would need to be updated by running git reset in the server’s copy.

This can be fixed by running this command on my local machine:

 git config --global receive.denyCurrentBranch "updateInstead"

So now when I try to push commits onto the current branch in the server’s copy it will automatically update the HEAD, provided there is no other uncommited changes hanging out in the working tree. RAD.

So when @github Copilot drops a line of code into my project it’s also going to drop in 200 million LICENSE files and attributions right? RIGHT?

We have access to Pfizer vaccine at my work. I reckon you could draw a line through the department separating who’s vaxxed and who’s ‘gonna do it soon’ by asking ‘Can you describe an expontential function?’.

My review of the ZSA Moonlander Ergonomic Keyboard: www.milesmcbain.com/posts/zsa…

Another riff on the placeholder idea with |>:

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
. <- function(.dat, template){
    template_code <- deparse(substitute(template)) 
    arg <- deparse(substitute(.dat))
    interpolated_code <- gsub("(?<=[(, ])?[.](?=[), \\[])", arg, template_code, perl = TRUE)
    eval(parse( text = interpolated_code))
}

"a" |>
 .(c(., "b")) |>
 .(setNames(., .))
#>   a   b 
#> "a" "b"

mtcars |> 
    transform(kmL = mpg / 2.35) |>
    .(lm(kmL ~ hp, data = .))
#> 
#> Call:
#> lm(formula = kmL ~ hp, data = transform(mtcars, kmL = mpg/2.35))
#> 
#> Coefficients:
#> (Intercept)           hp  
#>    12.80803     -0.02903

"col_name" |> 
  .(mutate(mtcars, . = "cool")) |>
  .(bind_cols(., .)) |>
  .(.[1, ])
#> New names:
#> * mpg -> mpg...1
#> * cyl -> cyl...2
#> * disp -> disp...3
#> * hp -> hp...4
#> * drat -> drat...5
#> * ...
#>           mpg...1 cyl...2 disp...3 hp...4 drat...5 wt...6 qsec...7 vs...8
#> Mazda RX4      21       6      160    110      3.9   2.62    16.46      0
#>           am...9 gear...10 carb...11 col_name...12 mpg...13 cyl...14 disp...15
#> Mazda RX4      1         4         4          cool       21        6       160
#>           hp...16 drat...17 wt...18 qsec...19 vs...20 am...21 gear...22
#> Mazda RX4     110       3.9    2.62     16.46       0       1         4
#>           carb...23 col_name...24
#> Mazda RX4         4          cool

^{Created on 2021-06-24 by the reprex package (v2.0.0)}

I call . the ‘neutering’ function.

The dog’s balls pattern is a thing. I didn’t name it.

This is the pattern:

mtcars |>
    transform(kmL = mpg / 2.35) |>
    ( \(df)
      lm(kmL ~ hp, data = df)
    )()

Copy pasta from this tweet.

Noisy syntax involving parentheses, including a werid empty pair hanging out in the breeze at the end. The easiest thing for beginners anyone to forget or accidentally unbalance.

So rather than reinvent the wheel, let’s take a quick look at how other programming languages with pipes have solved this issue.

Well there’s the Hack pipe and it uses a $$ placeholder to allow the user to set the position without making a lambda:

$x = vec[2,1,3]
  |> Vec\map($$, $a ==> $a * $a)
  |> Vec\sort($$);

But Hack? That’s a bit obscure.

What about Julia? Something more data sciencey and close to home. Well Julia uses a @pipe macro to, you guessed it, let the user deploy a placeholder to the arg position to be piped to:

@pipe a |> addX(_,6) + divY(4,_) |> println # 10.0

This macro theme is repeated in other languages. Checkout Clojure, it has so many pipes: -> pipe to first, ->> pipe to last, and ofcourse, as-> pipe to placeholder.

Okay so I am just cherry-picking examples. But the placeholder or placeholder/macro combination is a solution with precedent to the problem of how to pipe into an argument other than the first.

So let’s think now about R. We don’t have macros. Game over? No. R’s famed syntax malleability via lazy evaluation and syntax tree operations is how we get that kind of stuff done.

To fix Dog’s balls we’d be looking at some kind of function that manipulates the syntax tree. That is to say, it can turn:

a |> b(x, _) into a |> b(x, a)

Clearly, it needs to know about the symbols a and b(x, _) so it has to be an infix operator. Something like:

a %|>% b(x, _)

Where the %|>% function’s job is to rewrite the syntax tree by replacing any _ in the tree on its right-hand side, with the thing on its left-hand side. Easy done? Well, there is a recursion issue. It needs to rewrite:

a %|>% b(x, _) %|>% c(y, _) into c(y, b(x, a)) but details details.

I do think we can probably shave down some characters…. maybe drop the |? Still keeps the forward idea going.

And how do we feel about _… a bit Pearl-ish… maybe ? hmmm no that doesn’t inspire confidence… . ahhhh brief but firm - I like it. Putting it all together we have our new pipe:

a %>% b(x, .)

Now, I already know what you’re going to say, “This is not a pipe”.

With VSCode you can configure a keybinding to run artibrary #rstats code, including {rstudioapi} calls in just a matter of seconds. That code can refer to things like the current selection, cursor location, or the current file.

For example here’s me making myself a knit button, where the placeholder $$ refers to the current file:

{
    "description": "knit to html",
    "key": "ctrl+i",
    "command": "r.runCommandWithEditorPath",
    "when": "editorTextFocus",
    "args": "rmarkdown::render(\"$$\", output_format = rmarkdown::html_document(), output_dir = \".\", clean = TRUE)"
}

And here’s a shortcut that opens a window to interactively edit the spatial object the user has the cursor on or has selected. In this case $$ refers to that object:

{
    "key": "e",
    "name": "mapedit object",
    "type": "command",
    "command": "r.runCommandWithSelectionOrWord",
    "args": "mapedit::editMap(mapview::mapview($$))"
}

Snippets are also easy. There’s about 3 different ways to achieve inserting text, all in the same simple json config style:

{
    "key": "ctrl+shift+m",
    "command": "type",
    "when": "editorLangId == r || editorLangId == rmd && editorTextFocus",
    "args": { "text": " %>% " }
}

Although RStudio addins are supported in VSCode, many things popular addins do can be done with a few lines of config. It’s a keyboard shortcut lover’s dream - I’d argue even more so than ESS. RStudio users should campaign for this!

Here’s a little thing I was noodling with today. A drop in replacement for help() that pulls up the help file as an RMardkown document in your editor pane, not some weird special web browser window off to one side.

It’s reminiscent of the way help works in ESS/Emacs:

https://github.com/MilesMcBain/rmdocs

rmdocs

The advantages are:

• You don’t take your hands off the keyboard to browse help
• Search a help file using your standard editor shortcuts
• Run examples in the console using standard mechanism (e.g. ctrl + enter)
• Text and example code uses your editor fonts, themes, and plugins
• Remix and edit examples in-situ (!)
• Copy and paste using your keyboard only
• You get to parse markdown with your eyes

On the downside:

• At the moment you lose the links between help files. They’re not browsable (as in ESS).
• You have to parse markdown with your eyes

It would be possible to bring it on par with ESS, but it would take a bit of work on the VSCode side, and then the VSCode-R extension would have 2 modes to view help in. Is this a good thing? I am not sure. I think this is probably good enough to fill the aching void in my setup.

With just little more work it could be used as a keyboard shortcut in RStudio as well.

For the benefit of my future self and other lovers of #rstats debugging:

Kevin Ushey just shared an incredible little trick with me that I am still reeling from in this issue thread.

You can use it to get a stack trace for code that is getting stuck in infinite loops or just generally taking a really long time. You can use that stack trace to see where in the code execution flow is getting bogged down.

I was there hacking in timing code and print statements (aka banging rocks together) when Kevin dropped this construct:

withCallingHandlers({
  ..YOUR SLOW CODE HERE..
}, interrupt = function(e) browser())

Here’s an example of it working:

[ins] r$> my_bad <- function() {
            while(TRUE) {
              lapply(letters, I)
            }
          }

          withCallingHandlers({
            my_bad()
            }, interrupt = function(e) browser())
Called from: (function(e) browser())(list())

[ins] Browse[1]> traceback()
7: unique.default(c("AsIs", oldClass(x)))
6: unique(c("AsIs", oldClass(x)))
5: structure(x, class = unique(c("AsIs", oldClass(x))))
4: FUN(X[[i]], ...)
3: lapply(letters, I) at #3
2: my_bad() at #2
1: withCallingHandlers({
       my_bad()
   }, interrupt = function(e) browser())
   

So when I interrupted the code running in the console with CTRL+C, I was kicked into browse mode, and from there I could call traceback()!

I am still trying to figure out how to wield this new power. It seems that depending on where you interrupt it, you may or may not have traceback available. But if the stack trace is available are the environment frames?!

Noodling around with the idea I came up with this, which seemed to work consistently:

withCallingHandlers({
            my_bad()
            }, interrupt = function(e) traceback())

Sweeet!

There’s also a more powerful version that Kevin shared down the thread that allows resuming. That trapped me in a bit of a loop of my own, but that’s what you get when you play with MAGIC.

Update

Luke Tierney (Gandalf level wizard), chimed in with some info that this trick can be pulled off with:

options(interrupt = browser)

Wow!

But then that lead me to try:

options(interrupt = recover)

Which is epic!

In case you don’t know about recover you REALLY should have a go with it. It’s pretty special. So special I made a video about it: https://youtu.be/M5n_2jmdJ_8 .

A mature debate was had about whether #rstats’ new |> requires the use of “dog’s balls”, ()(), for lambdas with \(). Sadly it does. But it’s still kind of cool, and if you want to feel extra thankful for our benevolent overlords you could take a walk through the smouldering ashes of the JS native pipe train wreck: github.com/tc39/prop…