| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Pencil.App.Internal
Description
Internal implementation of Pencil's main functionality.
Synopsis
- type PencilApp = ReaderT Config (ExceptT PencilException IO)
- data PencilException
- toPencilException :: IOError -> Maybe PencilException
- isInvalidByteSequence :: IOError -> Bool
- isNoSuchFile :: IOError -> Bool
- printAsList :: [String] -> IO ()
Documentation
type PencilApp = ReaderT Config (ExceptT PencilException IO) Source #
The primary monad transformer stack for a Pencil application.
This unrolls to:
PencilApp a = Config -> IO (Except PencilException a)
The ExceptT monad allows us to catch "checked" exceptions; errors that we
know how to handle, in PencilException. Note that Unknown "unchecked"
exceptions can still go through IO.
data PencilException Source #
Known Pencil errors that we know how to either recover from or quit gracefully.
Constructors
| NotTextFile (Maybe FilePath) | Failed to read a file as a text file. |
| FileNotFound (Maybe FilePath) | File not found. We may or may not know the file we were looking for. |
| CollectionNotLastInStructure Text | The collection in the structure was not the last element in the structure. |
| CollectionFirstInStructure Text | A collection cannot be the first element in the structure (it's useless there, as nothing can reference the pages in the collection). |
Instances
| Show PencilException Source # | |
Defined in Pencil.App.Internal Methods showsPrec :: Int -> PencilException -> ShowS # show :: PencilException -> String # showList :: [PencilException] -> ShowS # | |
toPencilException :: IOError -> Maybe PencilException Source #
Converts the IOError to a known PencilException.
How to test errors:
import Control.Exception import qualified Data.Text.IO as TIO (e -> print (ioe_description(e :: IOError)) >> return "")handle(TIO.readFile "foo")
isInvalidByteSequence :: IOError -> Bool Source #
Returns true if the IOError is an invalid byte sequence error. This suggests that the file is a binary file.
isNoSuchFile :: IOError -> Bool Source #
Returns true if the IOError is due to missing file.
printAsList :: [String] -> IO () Source #
Print the list of Strings, one line at a time, prefixed with "-".