gistfile1.txt

-- GHC8
-- the below code is docCommentLine from src/Idris/Parser/Helpers.hs, contentsInner is the do block at lines 202-206
*Idris.Parser.Helpers> runparser (string "|||" >> many (satisfy (==' ')) >> option "" contentsInner  >>= \contents -> eol >> someSpace >> return contents) idrisInit "" "||| foo"
Success "foo"

*Idris.Parser.Helpers> let pars = string "|||" >> many (satisfy (==' ')) >> option "" contentsInner  >>= \contents -> eol >> someSpace >> return contents

*Idris.Parser.Helpers> runparser pars idrisInit "" "|||foo"
Failure (ErrInfo {_errDoc = :1:7: error: unexpected
    EOF, expected: end of line
|||foo<EOF> 
      ^     , _errDeltas = [Directed "" 0 6 6 6]})

*Idris.Parser.Helpers> :t runparser (string "|||" >> many (satisfy (==' ')) >> option "" contentsInner  >>= \contents -> eol >> someSpace >> return contents)
  :: TokenParsing (StateT st IdrisInnerParser) =>
     st -> String -> String -> Result [Char]

*Idris.Parser.Helpers> :t runparser pars
runparser pars :: st -> String -> String -> Result [Char]