| f g h |
f := '[ :a | ^a + 1 ].'. " Message pattern expected "
g := '| b |'. " '|' expected "
h := '| b ||'. " Success?!? "
OpalCompiler compile: f.
OpalCompiler compile: g.
OpalCompiler compile: h.

Basically I went from writing a function to clean up StringMorphs on the World...
 
cleanupStringMorph
  "Clean up string morph in world."
  | x y |
  x := World submorphs.
  y := [ x select: [ :each | (each isMemberOf: StringMorph) ] ].
  y value do: [ :each | each delete ].
  Smalltalk garbageCollect.
 
...to wondering how to generalize the idea (pass the class as an argument)...
...but that would be too easy, so why not manipulate the AST programatically...
I read https://marcusdenker.de/publications/Bera13a-OpalIWST.pdf but the compiler
thinks I am a fool :-(
 
My guess is I need to know what are the method calls from text to AST to bytecode.
Any idea?