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Remove pipes from multi-line REPL prompts #24307

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Merged
merged 3 commits into from
Nov 6, 2025
+1 −1
Merged

Remove pipes from multi-line REPL prompts #24307

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8ecff02
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lihaoyi Oct 29, 2025
7b8cc05
Merge branch 'main' into repl-prompt
lihaoyi Nov 1, 2025
e550559
fix
lihaoyi Nov 6, 2025
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10 changes: 5 additions & 5 deletions repl/src/dotty/tools/repl/JLineTerminal.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -33,12 +33,12 @@ class JLineTerminal extends java.io.Closeable {
builder.build()
private val history = new DefaultHistory

private def blue(str: String)(using Context) =
if (ctx.settings.color.value != "never") Console.BLUE + str + Console.RESET
private def purple(str: String)(using Context) =
if (ctx.settings.color.value != "never") Console.MAGENTA + str + Console.RESET
else str
protected def promptStr = "scala"
private def prompt(using Context) = blue(s"\n$promptStr> ")
private def newLinePrompt(using Context) = blue(" | ")
protected def promptStr = "@"
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@sjrd sjrd Nov 2, 2025

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@ is a cute symbol for ammonite (the name), but that cuteness does not apply for Scala in general. There's no precedent (that I know of) for this symbol being used as a general prompt anywhere.

I'm not against using a short prompt but then it should just be > like virtually all prompts in existence.

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@lihaoyi lihaoyi Nov 2, 2025 •
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A large motivation for the recent effort to renovate the REPL has been to merge all the useful parts of Ammonite into it: pretty-printed output, ctrl-c handling, library import, etc.. I expect Ammonite as a standalone project will go into maintenance mode soon after 3.8.0 is released.

Given that, @ looking like the Ammonite REPL is exactly what we want: for all intents and purposes, Ammonite going forward will be the default Scala REPL, and any association that people have with the @ symbol is exactly right.

We can come up with a new symbol, we can use > which is shared by a bunch of other REPLs. But @ is already widely known in the Scala community, has exactly the right associations (Scala REPL ++) and soon-to-be unambigious. So there's plenty of upsides of using this symbol and no long-term downsides

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@Gedochao Gedochao Nov 3, 2025

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Given that, @ looking like the Ammonite REPL is exactly what we want: for all intents and purposes, Ammonite going forward will be the default Scala REPL, and any association that people have with the @ symbol is exactly right.

...wait, slow down. While we very much appreciate all the improvements brought over from Ammonite REPL, Scala REPL remains its own thing. If anything, I think users may be confused with the @ being there. Some Ammonite REPL features won't be brought over (like the Ammonite style directives, for example).

I'm a fan of going with > myself, too.
We'll discuss how to move forward on Scala Core.

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@prolativ prolativ Nov 3, 2025

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Maybe instead of having long discussions, trying to figure out what would be best for users, maybe we could let them decide themselves? Personally, I've recently become a bit crazy about how one can make their life easier by customizing their shell prompt, but I wouldn't go too far for this moment. The prompt in the REPL could be configurable as a simple string (and maybe as a color) via a scala-cli flag (or potentially also via a directive to let people use a scala file as a template for REPL settings)

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@Gedochao Gedochao Nov 3, 2025

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...we probably could make whatever we decide on customisable, yeah. 😅

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@lihaoyi lihaoyi Nov 3, 2025

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I'm fine with > if that's what you all prefer, just let me know the decision and I'll update the PR

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@SethTisue SethTisue Nov 5, 2025

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I agree with the arguments against @

private def prompt(using Context) = purple(s"\n$promptStr ")
private def newLinePrompt(using Context) = purple(" ")
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@hamzaremmal hamzaremmal Nov 5, 2025

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This is my personal preference. If we were to have a > on the first line then maybe it's best to have one also in the lines after that to be able to easily keeps things aligned.

Suggested change
private def newLinePrompt(using Context) = purple(" ")
private def newLinePrompt(using Context) = purple(">")

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@lihaoyi lihaoyi Nov 5, 2025

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The problem with adding >s in subsequent lines is it makes copy paste harder. Without the > you just copy-paste-dedent, with the > you paste and the need to remove the > from each subsequent line, and also manually remove the space since it'll be one remaining space so a 2-space dedent doesnt work


/** Blockingly read line from `System.in`
*
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