experiment with removing transparent inline from op definitions

[erikerlandson]

An experiment in removing transparent inline on operators.

This branch removes transparent inline from the pow method.

[erikerlandson]

The results are interesting. The operator itself, in isolation, works, but it does lose important type information.

Welcome to Scala 3.1.1 (11.0.14, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
                                                                                                                                            
scala> import coulomb.*, algebra.instances.all.given, coulomb.ops.standard.given, coulomb.policy.standard.given
                                                                                                                                            
scala> import coulomb.units.us.{*,given}, coulomb.units.mks.{*,given}, coulomb.units.accepted.{*,given}
                                                                                                                                            
scala> 2d.withUnit[Meter].pow[3]
val res0: Any = 8.0
                                                                                                                                            
scala> res0.asInstanceOf[Quantity[Double, Meter ^ 3]]
val res1: coulomb.Quantity[Double, coulomb.units.us.Meter ^ 3] = 8.0
                                                                                                                                                                                                                                                                                        
scala> def f(q: Quantity[Double, Meter ^ 3]): Double = q.value
def f(q: coulomb.Quantity[Double, coulomb.units.us.Meter ^ 3]): Double
                                                                                                                                            
scala> f(res0)
-- [E007] Type Mismatch Error: -------------------------------------------------
1 |f(res0)
  |  ^^^^
  |  Found:    (res0 : Any)
  |  Required: coulomb.Quantity[Double, coulomb.units.us.Meter ^ (3 : Int)]

longer explanation available when compiling with `-explain`
1 error found
                                                                                                                                            
scala> 

From the above we can see that applying the pow operator succeeds, but without transparent inline the type of the operator is Any and so the coulomb unit type system isn't propagated in a useful way in operation outputs.

This is also reflected in the failures of the unit tests.

[erikerlandson]

Overall this does not seem viable. It might be possible to recover using the old Aux trick but that feels like backsliding to Scala 2

[armanbilge]

Question: instead of making this an anonymous class within the inline function, can we make it a named class outside that is then instantiated within the inline function? The problem with anonymous classes in inline functions is that means everywhere the function is inlined, you will get a completely new (anonymous) class. This causes code bloat, esp. on JS.

[erikerlandson]

I'll play around with it 👍

[erikerlandson]

See #265. If I'm understanding what you are thinking, it looks promising