#14917: Allow levity polymorhism in binding position -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: | LevityPolymorphism Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): I am a bit less optimistic than Richard (in comment:3). You imply that all the inlining could be done in the desugarer; but that can only work if you could see all calls. GHC does already have the notion of a "compulsory unfolding" (see `CoreSyn.UnfoldingSource`). Bindings with a compulsory unfolding ''do not have a binding at all'', so they must be inlined at every call site. That fits with the proposal here because we can't implement the levity- polymorphic code, so we can't compile code for it. We'd still somehow need to check that, after the inlining, the levity- polymorphism had vanished, and give a decent error message if not. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14917#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler