Partial function application prematurely runs codeblock when used with underscore

Question

Given:

def save(f: => Any)(run:Boolean) { if (run) { println(\"running f\"); f } else println(\"not running f\") } 

I can call it with:<

Answer 1

The behaviour of call-by-name parameters under eta expansion is currently under review, see this bug. Your code works as you expect (that is, the line save(throw new RuntimeException("boom!")) _ returns a function without throwing the exception) with recent nightly builds of 2.10. Let's see if it stays in until release!

See also this question for a related question on the general case of eta expansion not involving call-by-name.