Lambda Conversion Considered Harmful?

[Neal Gafter]

On Fri, Feb 19, 2010 at 3:36 PM, Joshua Bloch <jjb at google.com> wrote:

> Just to echo Alex's concerns, I was fooled by this, hence my statement that
> it was converting from one interface to another. JLS 3 (Section
> 5.1.5)<
> http://java.sun.com/docs/books/jls/third_edition/html/conversions.html
> >says
> "
> A *widening reference* conversion exists from any type *S* to any type *T*,
> provided *S* is a subtype
> (§4.10)<
> http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#120403
> >
>  of *T*."  The lambda conversion described in CfJ does not meet this
> specification, so it's wrong to call it a widening reference conversion.
>

This is clearly a bug in the JLS, otherwise the widening conversion from
byte to int would be a widening reference conversion.

CfJ's lambda conversion is defined as a widening conversion, but it isn't a
reference conversion.