Problem starting Ammonite REPL using Mill repl task

[enlambdment]

Hi everyone, I am trying to use the feature where I can start an Ammonite REPL that I can import the code defined in my Mill project: https://mill-build.org/mill/scalalib/module-config.html#_using_the_ammonite_repl_scala_console

I am using Scala 3. My Java version is also quite recent.

I recognize that unlike with console command, I may need to customize the Ammonite version being specified in the build.sc:

To use the repl, you can (and sometimes need to) customize the Ammonite version to work with your selected Scala version. Mill provides a default Ammonite version, but depending on the Scala version you are using, there may be no matching Ammonite release available. In order to start the repl, you may have to specify a different available Ammonite version.

However, it looks like no matter what versions I put for scalaVersion and ammoniteVersion, then using repl command results in the same error (after compile step finishes and succeeds):

Loading...
Welcome to the Ammonite Repl 3.0.0-M2 (Scala 3.3.1 Java 21.0.6)
stty: tcsetattr: Input/output error
stty: tcsetattr: Input/output error
Exception in thread "main" java.lang.RuntimeException: Nonzero exit value: 1
at scala.sys.process.ProcessBuilderImpl$AbstractBuilder.slurp(ProcessBuilderImpl.scala:164)
at scala.sys.process.ProcessBuilderImpl$AbstractBuilder.$bang$bang(ProcessBuilderImpl.scala:121)
at ammonite.terminal.TTY$.stty(Utils.scala:106)
at ammonite.terminal.TTY$.withSttyOverride(Utils.scala:122)
at ammonite.terminal.Terminal$.readLine(Terminal.scala:38)
at ammonite.repl.AmmoniteFrontEnd.readLine(AmmoniteFrontEnd.scala:160)
at ammonite.repl.AmmoniteFrontEnd.action(AmmoniteFrontEnd.scala:30)
at ammonite.repl.Repl.action$$anonfun$2$$anonfun$2(Repl.scala:205)
at ammonite.repl.Scoped.flatMap$$anonfun$1(Signaller.scala:45)
at ammonite.repl.Signaller.apply(Signaller.scala:28)
at ammonite.repl.Scoped.flatMap(Signaller.scala:45)
at ammonite.repl.Scoped.flatMap$(Signaller.scala:42)
at ammonite.repl.Signaller.flatMap(Signaller.scala:16)
at ammonite.repl.Repl.action$$anonfun$2(Repl.scala:211)
at ammonite.util.Res$Success.flatMap(Res.scala:58)
at ammonite.repl.Repl.action(Repl.scala:211)
at ammonite.repl.Repl.loop$1(Repl.scala:218)
at ammonite.repl.Repl.run(Repl.scala:233)
at ammonite.Main.run(Main.scala:249)
at ammonite.MainRunner.runRepl$$anonfun$1(MainRunner.scala:76)
at ammonite.MainRunner.watchLoop(MainRunner.scala:57)
at ammonite.MainRunner.runRepl(MainRunner.scala:76)
at ammonite.AmmoniteMain$.main0(AmmoniteMain.scala:98)
at ammonite.AmmoniteMain$.main(AmmoniteMain.scala:31)
at ammonite.AmmoniteMain.main(AmmoniteMain.scala)

My mill script is as follows (I think I just copied an example from the Mill GitHub and then bumped the Mill version):

/#!/usr/bin/env sh

/# This is a wrapper script, that automatically download mill from GitHub release pages
/# You can give the required mill version with MILL_VERSION env variable
/# If no version is given, it falls back to the value of DEFAULT_MILL_VERSION
DEFAULT_MILL_VERSION=0.11.13

set -e

if [ -z "$MILL_VERSION" ] ; then
if [ -f ".mill-version" ] ; then
MILL_VERSION="$(head -n 1 .mill-version 2> /dev/null)"
elif [ -f "mill" ] && [ "$BASH_SOURCE" != "mill" ] ; then
MILL_VERSION=$(grep -F "DEFAULT_MILL_VERSION=" "mill" | head -n 1 | cut -d= -f2)
else
MILL_VERSION=$DEFAULT_MILL_VERSION
fi
fi

if [ "x${XDG_CACHE_HOME}" != "x" ] ; then
MILL_DOWNLOAD_PATH="${XDG_CACHE_HOME}/mill/download"
else
MILL_DOWNLOAD_PATH="${HOME}/.cache/mill/download"
fi
MILL_EXEC_PATH="${MILL_DOWNLOAD_PATH}/${MILL_VERSION}"

version_remainder="$MILL_VERSION"
MILL_MAJOR_VERSION="${version_remainder%%.}"; version_remainder="${version_remainder#.}"
MILL_MINOR_VERSION="${version_remainder%%.}"; version_remainder="${version_remainder#.}"

if [ ! -x "$MILL_EXEC_PATH" ] ; then
mkdir -p $MILL_DOWNLOAD_PATH
if [ "$MILL_MAJOR_VERSION" -gt 0 ] || [ "$MILL_MINOR_VERSION" -ge 5 ] ; then
ASSEMBLY="-assembly"
fi
DOWNLOAD_FILE=$MILL_EXEC_PATH-tmp-download
MILL_DOWNLOAD_URL="https://github.com/lihaoyi/mill/releases/download/${MILL_VERSION%%-*}/$MILL_VERSION${ASSEMBLY}"
curl --fail -L -o "$DOWNLOAD_FILE" "$MILL_DOWNLOAD_URL"
chmod +x "$DOWNLOAD_FILE"
mv "$DOWNLOAD_FILE" "$MILL_EXEC_PATH"
unset DOWNLOAD_FILE
unset MILL_DOWNLOAD_URL
fi

unset MILL_DOWNLOAD_PATH
unset MILL_VERSION

exec $MILL_EXEC_PATH "$@"

I did see this comment from an earlier discussion but am not sure what it means. Is this saying that the Ammonite-based Mill REPL is deprecated from Mill 0.11 onwards (and I should only use e.g. ./mill impl.console from now on)?

[lefou]

I think you should try a newer Ammonite version (or tell us exactly what versions you already tested and how). Ammonite 3.0.0-M2 is quite old. I think 3.0.0-15-c7a11918 is the latest version, which should support Scala up to 3.6.2. Mill should work properly with up to Java 23 I think.

Your mill launch script looks also old to me, although it should not be the issue here.

The other discussion you mentioned was not about the .repl command but the --repl cli arg, which is no longer available in newer Mill versions.

[enlambdment]

I think you should try a newer Ammonite version (or tell us exactly what versions you already tested and how). Ammonite 3.0.0-M2 is quite old. I think 3.0.0-15-c7a11918 is the latest version, which should support Scala up to 3.6.2. Mill should work properly with up to Java 23 I think.

Thank you for the tip about using a newer Ammonite per whatever Scala I choose.

Since I don't see any path under the Central Repository for com/lihaoyi namespace that corresponds to Ammonite 3.6.2 (expecting to see it at: https://repo1.maven.org/maven2/com/lihaoyi/ammonite_3.6.2), it makes me think that there isn't anything available to download:

% ./mill impl.repl
[83/91] impl.resolvedAmmoniteReplIvyDeps | Downloading [2/2] artifacts (~0/0 bytes)
1 targets failed
impl.resolvedAmmoniteReplIvyDeps 
Resolution failed for 1 modules:
--------------------------------------------
  com.lihaoyi:ammonite_3.6.2:3.0.0-15-c7a11918 
	not found: https://repo1.maven.org/maven2/com/lihaoyi/ammonite_3.6.2/3.0.0-15-c7a11918/ammonite_3.6.2-3.0.0-15-c7a11918.pom

--------------------------------------------

For additional information on library dependencies, see the docs at
https://mill-build.org/mill/Library_Dependencies.html

However: I was able to

1. go to the ^ central repository linked above
2. select the link for all versions under ammonite_3.3.1 (downgrading the Scala I will use in build.sc)
3. then pick the ammonite version which appears most recent
4. and copy those into the build.sc

So with the following, I was able to get things working. (though see the note below):

import mill._, scalalib._
import mill.scalalib.TestModule


object api extends ScalaModule {
  def scalaVersion = "3.3.1"
  def ammoniteVersion = "3.0.0-M2-30-486378af"

  def ivyDeps = Agg(
    ivy"org.typelevel::cats-core:2.13.0"
  )
}

object impl extends ScalaModule {
  def scalaVersion = "3.3.1"
  def ammoniteVersion = "3.0.0-M2-30-486378af"
  def moduleDeps = Seq(api)

  def ivyDeps = Agg(
    ivy"org.typelevel::cats-core:2.13.0"
  )

  object test extends ScalaTests with TestModule.Utest {
    def ivyDeps = Agg(
       ivy"com.lihaoyi::utest:0.8.5",
       ivy"org.scalacheck::scalacheck:1.17.1"
     )
    def testFrameworks = Seq("utest.runner.Framework")
  }
}

Your mill launch script looks also old to me, although it should not be the issue here.

The other discussion you mentioned was not about the .repl command but the --repl cli arg, which is no longer available in newer Mill versions.

I see, thank you for clarifying. I'm not sure what the significance of this is, but:

I tried falling back on the console command which (I think) just uses the global system Scala

% ./mill impl.console
[92/92] impl.console 
1 targets failed
impl.console console needs to be run with the -i/--interactive flag

and it made me think "perhaps the same flag is required for repl command also."

In fact: when I ran instead ./mill -i impl.repl using -i flag, I no longer get the error about "stty: tcsetattr: Input/output error". It launches an Ammonite REPL that seems to work fine (tab completion, etc.)

% ./mill -i impl.repl
[91/91] impl.repl 
Loading...
Welcome to the Ammonite Repl 3.0.0-M2-30-486378af (Scala 3.3.1 Java 21.0.6)
@ import impl.[TAB]
SLList               ArrayBackedBag       ArrayStack           Node                 ArrayBackedBag       ... etc. ...

I didn't remember seeing this anywhere in the docs but maybe I just didn't read closely enough. In any case though, it looks like I was just missing the -i flag. Thanks for the help!