Maybe String -> CoreExpr in a GHC plugin
Hi, in a GHC plugin, I want to synthesize simple data structures, and insert them into the code. What is the most idiomatic way of writing a function, say, foo :: Maybe String -> CoreExpr or foo :: Maybe String -> CoreM CoreExpr so that the resulting CoreExpr describes the input. Abstractly speaking, I could imagine creating the Core AST by hand (but I’d have to figure out how to resolve the names of the constructors), or somehow invoking the renamer, type-checker and desugarer from within CoreM. Surely someone else has solved this problem before. How did you do it? Thanks, Joachim -- Joachim “nomeata” Breitner mail@joachim-breitner.de https://www.joachim-breitner.de/
Hi, Am Dienstag, den 16.01.2018, 11:08 -0500 schrieb Joachim Breitner:
in a GHC plugin, I want to synthesize simple data structures, and insert them into the code. What is the most idiomatic way of writing a function, say,
foo :: Maybe String -> CoreExpr
or
foo :: Maybe String -> CoreM CoreExpr
so that the resulting CoreExpr describes the input. Abstractly speaking, I could imagine creating the Core AST by hand (but I’d have to figure out how to resolve the names of the constructors), or somehow invoking the renamer, type-checker and desugarer from within CoreM.
I ended up writing this: dcExpr :: TH.Name -> CoreM CoreExpr dcExpr thn = do Just name <- thNameToGhcName thn dc <- lookupDataCon name pure $ Var (dataConWrapId dc) resultToExpr :: Result -> CoreM CoreExpr resultToExpr (Success s) = App <$> dcExpr 'Success <*> mkStringExpr s resultToExpr (Failure s) = App <$> dcExpr 'Failure <*> mkStringExpr s which seems to work fine. Cheers, Joachim -- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/
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Joachim Breitner