Parsing UnicodeSyntax with haskell-src-exts
haskell, haskell-src-exts
Solution
From a cursory glance at the source, it doesn't look like `parseModule` extracts language pragmas from the source before parsing (`parseFile` does do that by calling `getExtensions`). By the time parsing has begun, it is already too late to enable unicode syntax.
Problem
I have a Haskell source file which using Unicode syntax: ``` {-# LANGUAGE UnicodeSyntax #-} succ' :: Int → Int succ' = succ main :: IO () main = print $ succ' 1 ``` This parses and runs fine with GHC. Additionally, stylish-haskell and hlint (both based on haskell-src-exts) can read this file without any trouble. However, when I try to parse it myself using haskell-src-exts: ``` import Language.Haskell.Exts (parseModule) main = do x <- readFile "test.hs" print $ parseModule x ``` I get the error message: ``` ParseFailed (SrcLoc {srcFilename = "<unknown>.hs", srcLine = 6, srcColumn = 1}) "TypeOperators is not enabled" ``` However, providing UnicodeSyntax explicitly in the extensions list or using parseFile works just fine: ``` import Language.Haskell.Exts main = do x <- readFile "test.hs" print $ parseModuleWithMode defaultParseMode { extensions = [UnicodeSyntax] } x parseFile "test.hs" >>= print ``` Any idea why the first approach fails?