print not accepted in task definition in SBT 0.13? - sbt

Question

I'm using SBT 0.13.1.
project/build.properties is as follows:
sbt.version=0.13.1
Executing sbt about prints out the following:
$ sbt
[info] Loading global plugins from /Users/jacek/.sbt/0.13/plugins
[info] Loading project definition from /Users/jacek/sandbox/so/sbt-0.13.1/project
[info] Set current project to sbt-0-13-1 (in build file:/Users/jacek/sandbox/so/sbt-0.13.1/)
[sbt-0-13-1]> about
[info] This is sbt 0.13.1
[info] The current project is {file:/Users/jacek/sandbox/so/sbt-0.13.1/}sbt-0-13-1 0.1-SNAPSHOT
[info] The current project is built against Scala 2.10.4-RC1
[info] Available Plugins: com.typesafe.sbt.SbtGit, com.typesafe.sbt.SbtProguard, growl.GrowlingTests, np.Plugin, net.virtualvoid.sbt.graph.Plugin, com.timushev.sbt.updates.UpdatesPlugin
[info] sbt, sbt plugins, and build definitions are using Scala 2.10.3
With the following task - hello - in build.sbt:
scalaVersion := "2.10.4-RC1"
lazy val hello = taskKey[Unit]("An example task")
hello := {
print("Sleeping for a sec...")
println("done.")
}
...and reload, sbt reports [error] Type error in expression:
[sbt-0-13-1]> reload
[info] Loading global plugins from /Users/jacek/.sbt/0.13/plugins
[info] Loading project definition from /Users/jacek/sandbox/so/sbt-0.13.1/project
/Users/jacek/sandbox/so/sbt-0.13.1/build.sbt:6: error: type mismatch;
found : String("Sleeping for a sec...")
required: sbt.TaskKey[String]
print("Sleeping for a sec...")
^
[error] Type error in expression
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore?
When I change print to println the task is defined correctly.
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore? r
[info] Loading global plugins from /Users/jacek/.sbt/0.13/plugins
[info] Loading project definition from /Users/jacek/sandbox/so/sbt-0.13.1/project
[info] Set current project to sbt-0-13-1 (in build file:/Users/jacek/sandbox/so/sbt-0.13.1/)
[sbt-0-13-1]> hello
Sleeping for a sec...
done.
[success] Total time: 0 s, completed Jan 4, 2014 10:31:43 AM
Is print not accepted in task definition?

Answer 1

With the help of schleichardt I could finally find out what has caused the issue of not accepting print in the hello task.
It turned out that with the sbt-dependency-graph plugin in the global configuration directory, i.e. ~/.sbt/0.13/ (or a directory specified by sbt.global.base), sbt couldn't initialize the task and hence the error.
$ cat plugins/sbt-dependency-graph.sbt
addSbtPlugin("net.virtual-void" % "sbt-dependency-graph" % "0.7.4")
$ cat sbt-dependency-graph.sbt
net.virtualvoid.sbt.graph.Plugin.graphSettings
To reproduce, see the following sbt session starting with print (not println) in build.sbt and empty global configuration directory:
jacek:~/sandbox/so/sbt-0.13.1
$ tree
.
├── build.sbt
└── project
└── build.properties
1 directory, 2 files
jacek:~/sandbox/so/sbt-0.13.1
$ cat build.sbt
scalaVersion := "2.10.4-RC1"
lazy val hello = taskKey[Unit]("An example task")
hello := {
print("Sleeping for a sec...")
println("done.")
}
jacek:~/sandbox/so/sbt-0.13.1
$ sbt -Dsbt.global.base=/tmp/so
Getting org.scala-sbt sbt 0.13.1 ...
:: retrieving :: org.scala-sbt#boot-app
confs: [default]
43 artifacts copied, 0 already retrieved (12646kB/154ms)
Getting Scala 2.10.3 (for sbt)...
:: retrieving :: org.scala-sbt#boot-scala
confs: [default]
5 artifacts copied, 0 already retrieved (24447kB/204ms)
[info] Loading project definition from /Users/jacek/sandbox/so/sbt-0.13.1/project
[info] Updating {file:/Users/jacek/sandbox/so/sbt-0.13.1/project/}sbt-0-13-1-build...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Set current project to sbt-0-13-1 (in build file:/Users/jacek/sandbox/so/sbt-0.13.1/)
> hello
Sleeping for a sec...done.
[success] Total time: 0 s, completed Jan 4, 2014 1:35:22 PM
It works so far.
Create the files for the sbt-dependency-graph plugin in the global configuration directory.
jacek:/tmp/so
$ cat plugins/sbt-dependency-graph.sbt
addSbtPlugin("net.virtual-void" % "sbt-dependency-graph" % "0.7.4")
jacek:/tmp/so
$ cat sbt-dependency-graph.sbt
net.virtualvoid.sbt.graph.Plugin.graphSettings
...and reload.
> reload
[info] Loading global plugins from /private/tmp/so/plugins
[info] Updating {file:/tmp/so/plugins/}global-plugins...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Loading project definition from /Users/jacek/sandbox/so/sbt-0.13.1/project
[info] Updating {file:/Users/jacek/sandbox/so/sbt-0.13.1/project/}sbt-0-13-1-build...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
/Users/jacek/sandbox/so/sbt-0.13.1/build.sbt:6: error: type mismatch;
found : String("Sleeping for a sec...")
required: sbt.TaskKey[String]
print("Sleeping for a sec...")
^
[error] Type error in expression
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore?
When print changes to println and (r)etry, it works fine again.
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore? r
[info] Loading global plugins from /private/tmp/so/plugins
[info] Loading project definition from /Users/jacek/sandbox/so/sbt-0.13.1/project
[info] Set current project to sbt-0-13-1 (in build file:/Users/jacek/sandbox/so/sbt-0.13.1/)
> hello
Sleeping for a sec...
done.
[success] Total time: 0 s, completed Jan 4, 2014 1:43:59 PM