Is the meta programming allowed in REPL?

[plokhotnyuk]

I have tried to run an example from the Principled Meta Programming doc page.

1. It seems that some import is missing to compile with the showExpr call.
2. Even after successful compilation without that call I cannot use the assert macro:

andriy@notebook:~/Downloads/dotty-0.10.0/bin$ ./dotr
Starting dotty REPL...
scala> import scala.quoted._                                                                                                                                                                                       
     | 
     | inline def assert(expr: => Boolean): Unit =
     |   ~ assertImpl('(expr))
     | 
     | def assertImpl(expr: Expr[Boolean]) =
     |   '{ if !(~expr) then throw new AssertionError("failed assertion")}
def assert(expr: => Boolean): Unit
def assertImpl(expr: quoted.Expr[Boolean]): quoted.Expr[Unit]

scala> assert(0 == 0)
1 |assert(0 == 0)
  |^^^^^^^^^^^^^^
  |Could not find macro class rs$line$1$ in classpath. The most common reason for that is that you apply macros in the compilation run that defines them

[nicolasstucki]

1. showExpr is actually defined below in the document. Though its definition is also wrong (outdated) (improves with Improve showExpr example #5562).
2. As far as I can see it should be possible to define macros in the REPL. Most likely the macro classloader gets confused by the special classloader that the REPL uses.