Github user aalexandrov commented on the pull request:
https://github.com/apache/flink/pull/1217#issuecomment-148901986
> Not all methods without paremeters should translate to methods without
parenthesis...
@StephanEwen I agree with that, but I cannot understand how the
`UnitTypeInfo` might cause a confusion here.
The typeInformation macros are synthesized by the macro based on the
inferred collection type, which means that the meaning of `()` is resolved
before that. Consider the following example:
```scala
// in the Scala REPL
case class Foo(answer: Int)
// defined class Foo
def f1(): Foo = Foo(42)
// f1: ()Foo
def f2: Foo = Foo(42)
// f2: Foo
val xs = Seq(f1(), f2) // how a literate person would write it
// xs: Seq[Foo] = List(Foo(42), Foo(42))
val xs = Seq(f1, f2) // how a dazed & confused person would write it, but
still compiles
// xs: Seq[Foo] = List(Foo(42), Foo(42))
val xs = Seq(f1, f2()) // even worse, but this breaks with a compiler
exception
// error: Foo does not take parameters
// val xs = Seq(f1, f2())
val xs = Seq((), ()) // typing '()' without syntactic context resolves to
Unit
// xs: Seq[Unit] = List((), ())
```
In all of the above situations `env.fromCollection(xs)` is (1) either going
to typecheck and trigger `TypeInformation` synthesis or (2) fail with the above.
Can you point to StackOverflow conversation or something similar where the
issue you mention is explained with an example?
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