diff options
Diffstat (limited to 'compiler/GHC/Tc/Gen/Splice.hs')
| -rw-r--r-- | compiler/GHC/Tc/Gen/Splice.hs | 37 |
1 files changed, 20 insertions, 17 deletions
diff --git a/compiler/GHC/Tc/Gen/Splice.hs b/compiler/GHC/Tc/Gen/Splice.hs index 48464f5ca5..c42dd689fa 100644 --- a/compiler/GHC/Tc/Gen/Splice.hs +++ b/compiler/GHC/Tc/Gen/Splice.hs @@ -213,11 +213,11 @@ tcTypedBracket rn_expr expr res_ty ; ps' <- readMutVar ps_ref ; codeco <- tcLookupId unsafeCodeCoerceName ; bracket_ty <- mkAppTy m_var <$> tcMetaTy expTyConName - ; tcWrapResultO (Shouldn'tHappenOrigin "TExpBr") -- romes TODO: What is Shouldn'tHappenOrigin? Is this still accurate? + ; tcWrapResultO (Shouldn'tHappenOrigin "TH typed bracket expression") rn_expr (unLoc (mkHsApp (mkLHsWrap (applyQuoteWrapper wrapper) (nlHsTyApp codeco [rep, expr_ty])) - (noLocA (HsTypedBracket (HsBracketTc expr bracket_ty (Just wrapper) ps') tc_expr)))) + (noLocA (HsTypedBracket (HsBracketTc (ExpBr noExtField expr) bracket_ty (Just wrapper) ps') tc_expr)))) meta_ty res_ty } -- See Note [Typechecking Overloaded Quotes] @@ -244,6 +244,7 @@ tcUntypedBracket rn_expr brack ps res_ty -- type ; tcWrapResultO BracketOrigin rn_expr (HsUntypedBracket (HsBracketTc brack expected_type brack_info ps') (XQuote noExtField)) + -- (XQuote noExtField): see Note [The life cycle of a TH quotation] in GHC.Hs.Expr expected_type res_ty } @@ -362,44 +363,46 @@ Remember, there are two forms of bracket and untyped [| e |] The life cycle of a typed bracket: - * Starts as HsBracket + * Starts as HsTypedBracket * When renaming: * Set the ThStage to (Brack s RnPendingTyped) * Rename the body - * Result is still a HsBracket + * Result is a HsTypedBracket * When typechecking: * Set the ThStage to (Brack s (TcPending ps_var lie_var)) - * Typecheck the body, and throw away the elaborated result + * Typecheck the body, and keep the elaborated result (despite never using it!) * Nested splices (which must be typed) are typechecked, and the results accumulated in ps_var; their constraints accumulate in lie_var - * Result is a HsTcBracketOut rn_brack pending_splices - where rn_brack is the incoming renamed bracket + * Result is a HsTypedBracket (HsBracketTc rn_brack ty quote_wrapper pending_splices) tc_brack + where rn_brack is the untyped renamed exp quote constructed from the typed renamed expression :: HsQuote GhcRn --- romes TODO update note The life cycle of a un-typed bracket: - * Starts as HsBracket + * Starts as HsUntypedBracket * When renaming: * Set the ThStage to (Brack s (RnPendingUntyped ps_var)) * Rename the body * Nested splices (which must be untyped) are renamed, and the results accumulated in ps_var - * Result is still (HsRnBracketOut rn_body pending_splices) + * Result is a HsUntypedBracket pending_splices rn_body - * When typechecking a HsRnBracketOut + * When typechecking: * Typecheck the pending_splices individually * Ignore the body of the bracket; just check that the context expects a bracket of that type (e.g. a [p| pat |] bracket should be in a context needing a (Q Pat) - * Result is a HsTcBracketOut rn_brack pending_splices - where rn_brack is the incoming renamed bracket + * Result is a HsUntypedBracket (HsBracketTc rn_brack ty quote_wrapper pending_splices) (XQuote noExtField) + where rn_brack is the incoming renamed bracket :: HsQuote GhcRn + and (XQuote noExtField) stands for the removal of the `HsQuote GhcTc` field (since `HsQuote GhcTc` isn't possible) +See the related Note [The life cycle of a TH quotation] In both cases, desugaring happens like this: - * HsTcBracketOut is desugared by GHC.HsToCore.Quote.dsBracket. It + * Hs*Bracket is desugared by GHC.HsToCore.Quote.dsBracket using the renamed + expression held in `HsBracketTc` (`type instance X*Bracket GhcTc = HsBracketTc`). It a) Extends the ds_meta environment with the PendingSplices attached to the bracket @@ -421,11 +424,11 @@ In both cases, desugaring happens like this: Example: Source: f = [| Just $(g 3) |] - The [| |] part is a HsBracket + The [| |] part is a HsUntypedBracket GhcPs Typechecked: f = [| Just ${s7}(g 3) |]{s7 = g Int 3} - The [| |] part is a HsBracketOut, containing *renamed* - (not typechecked) expression + The [| |] part is a HsUntypedBracket GhcTc, containing *renamed* + (not typechecked) expression (see Note [The life cycle of a TH quotation]) The "s7" is the "splice point"; the (g Int 3) part is a typechecked expression |