Cannot define a no-args closure in Groovy Shell

1. I wanted to define this very simple no-args closure, foo, using groovysh:

def foo = { ->
        println "test"
}

2. But the moment I hit ENTER in the shell after typing out the first line,
I get the following error:

$ groovysh
Groovy Shell (2.1.5, JVM: 1.6.0_43)
Type 'help' or '\h' for help.
-----------------------------------------------------------------------------------
groovy:000> def foo = { ->
ERROR org.codehaus.groovy.control.MultipleCompilationErrorsException:
startup failed:
groovysh_parse: 2: unexpected token: -> @ line 2, column 13.
def foo = { ->
^
1 error
at java_lang_Runnable$run.call (Unknown Source)

source: http://groovy.329449.n5.nabble.com/groovysh-bug-Cannot-define-a-no-args-closure-which-I-can-define-outside-of-it-td5716267.html