Valid java 5 code refuses to compile with lambda-8-b81-linux-x64-12_mar_2013

[Sam Pullara]

Looks like the confusion is in type inference. If you have an explicit
type it does work:

        <B, C> List<C> bind(final List<B> lb, final Func<A, Func<B, C>> f) {
            List<Func<B, C>> map = map(f);
            return lb.apply(map);
        }

Sam

On Sat, Mar 16, 2013 at 4:17 PM, Grégoire Neuville
<gregoire.neuville at gmail.com> wrote:
> Hello,
>
> First of all, let me thank and congratulate you for the hard work you're
> putting into adding a functional tone to java : this is a great move that
> will undoubtedly prove itself immensely beneficial.
>
> That being said, I'm having a hard time compiling some basic java 5 code
> with the binary pre-release of both the bare jdk 1.8 and the
> lambda-enriched one. Indeed, trying to compile the below code :
>
> <code>
>
>  public class TestJ8 {
>
>     interface Func<A, B> {
>         B f(A a);
>     }
>
>     class List<A> {
>
>         <B> List<B> map(Func<A, B> f) {
>             return null;
>         }
>
>         <B> List<B> bind(Func<A, List<B>> f) {
>             return null;
>         }
>
>         <B> List<B> apply(final List<Func<A, B>> lf) {
>             return lf.bind(this::map);
>         }
>
>         <B, C> List<C> bind(final List<B> lb, final Func<A, Func<B, C>> f) {
>             return lb.apply(map(f)); // fails to compile
>         }
>
>     }
>
> }
>
> </code>
>
> fails with the given message :  error: method apply in class TestJ8.List<A>
> cannot be applied to given types
>
> Is it expected behaviour or am I missing something (installation steps or
> whatever...) ?
>
> Note : The compiler is invoked through maven with the following
> configuration :
>
> <plugin>
>             <groupId>org.apache.maven.plugins</groupId>
>             <artifactId>maven-compiler-plugin</artifactId>
>             <version>3.0</version>
>             <configuration>
>                 <verbose>true</verbose>
>                 <fork>true</fork>
>                 <executable>/usr/lib/jvm/java8/bin/javac</executable>
>                 <compilerArgument>-g</compilerArgument>
>                 <compilerVersion>1.8</compilerVersion>
>                 <source>1.8</source>
>                 <target>1.8</target>
>             </configuration>
> </plugin>
>
> Thanks !
>
> --
> Grégoire Neuville
>