Layout problem in arrows code

[nibro]

Reported by Paul Liu:

exp = proc () -> do
  rec let e = 1 + i
      i <- integral -< e
  returnA -< e

gives an error: "Parse error: VRightCurly". A layout problem surely.

[nibro]

Turns out that it wasn't a layout problem after all (thank goodness!), but the fact that the rules for a stmtlist were written so that the last statement in a block has to be an expression (qualifier). That's obviously not true for rec blocks. Some rewiring of the productions, and refactoring that test out into a separate check for do (and mdo) blocks, and this now parses nicely in 1.1.1. Case closed.