diff options
author | Paul Phillips <paulp@improving.org> | 2013-04-19 15:01:46 -0700 |
---|---|---|
committer | Paul Phillips <paulp@improving.org> | 2013-04-20 15:25:53 -0700 |
commit | c29405dfe1a24419ce4ce10500b5e8d05c581bee (patch) | |
tree | dca5ea3a915101613b6d007831d9240596b685f5 /test/files/presentation | |
parent | d506bedc5ab83bf9af8cc0240e61a0c691f8508b (diff) | |
download | scala-c29405dfe1a24419ce4ce10500b5e8d05c581bee.tar.gz scala-c29405dfe1a24419ce4ce10500b5e8d05c581bee.tar.bz2 scala-c29405dfe1a24419ce4ce10500b5e8d05c581bee.zip |
Simplify type bounds.
I started out looking to limit the noise from empty type
bounds, i.e. the endless repetition of
class A[T >: _root_.scala.Nothing <: _root_.scala.Any]
This led me to be reminded of all the unnecessary and
in fact damaging overreaches which are performed during parsing.
Why should a type parameter for which no bounds are
specified be immediately encoded with this giant tree:
TypeBounds(
Select(Select(Ident(nme.ROOTPKG), tpnme.scala_), tpnme.Nothing),
Select(Select(Ident(nme.ROOTPKG), tpnme.scala_), tpnme.Any)
)
...which must then be manually recognized as empty type bounds?
Truly, this is madness.
- It deftly eliminates the possibility of recognizing
whether the user wrote "class A[T]" or "class A[T >: Nothing]"
or "class A[T <: Any]" or specified both bounds. The fact
that these work out the same internally does not imply the
information should be exterminated even before parsing completes.
- It burdens everyone who must recognize type bounds trees,
such as this author
- It is far less efficient than the obvious encoding
- It offers literally no advantage whatsoever
Encode empty type bounds as
TypeBounds(EmptyTree, EmptyTree)
What could be simpler.
Diffstat (limited to 'test/files/presentation')
-rw-r--r-- | test/files/presentation/callcc-interpreter.check | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/test/files/presentation/callcc-interpreter.check b/test/files/presentation/callcc-interpreter.check index af0154fe60..804b365101 100644 --- a/test/files/presentation/callcc-interpreter.check +++ b/test/files/presentation/callcc-interpreter.check @@ -69,13 +69,13 @@ retrieved 63 members askType at CallccInterpreter.scala(14,21) ================================================================================ [response] askTypeAt at (14,21) -def unitM[A >: Nothing <: Any](a: A): callccInterpreter.M[A] = callccInterpreter.this.M.apply[A](((c: A => callccInterpreter.Answer) => c.apply(a))) +def unitM[A](a: A): callccInterpreter.M[A] = callccInterpreter.this.M.apply[A](((c: A => callccInterpreter.Answer) => c.apply(a))) ================================================================================ askType at CallccInterpreter.scala(16,12) ================================================================================ [response] askTypeAt at (16,12) -def id[A >: Nothing <: Any]: A => A = ((x: A) => x) +def id[A]: A => A = ((x: A) => x) ================================================================================ askType at CallccInterpreter.scala(17,25) |