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https://github.com/idris-lang/Idris2.git
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235 lines
7.7 KiB
Idris
235 lines
7.7 KiB
Idris
module System.File.ReadWrite
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import public Data.Fuel
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import Data.List
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import Data.SnocList
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import System.File.Handle
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import public System.File.Error
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import System.File.Support
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import public System.File.Types
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%default total
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%foreign support "idris2_seekLine"
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"node:support:seekLine,support_system_file"
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prim__seekLine : FilePtr -> PrimIO Int
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%foreign support "idris2_readLine"
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"node:support:readLine,support_system_file"
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prim__readLine : FilePtr -> PrimIO (Ptr String)
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%foreign support "idris2_readChars"
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prim__readChars : Int -> FilePtr -> PrimIO (Ptr String)
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%foreign "C:fgetc,libc 6"
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prim__readChar : FilePtr -> PrimIO Int
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%foreign support "idris2_writeLine"
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"node:lambda:(filePtr, line) => require('fs').writeSync(filePtr.fd, line, undefined, 'utf-8')"
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prim__writeLine : FilePtr -> String -> PrimIO Int
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%foreign support "idris2_eof"
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"node:lambda:x=>(x.eof?1:0)"
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prim__eof : FilePtr -> PrimIO Int
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%foreign support "idris2_removeFile"
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prim__removeFile : String -> PrimIO Int
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||| Seek through the next newline.
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||| This is @fGetLine@ without the overhead of copying
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||| any characters.
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|||
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||| @ h the file handle to seek through
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export
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fSeekLine : HasIO io => (h : File) -> io (Either FileError ())
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fSeekLine (FHandle f)
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= do res <- primIO (prim__seekLine f)
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if res /= 0
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then returnError
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else ok ()
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||| Get the next line from the given file handle, returning the empty string if
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||| nothing was read.
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||| @ h the file handle to get the line from
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export
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fGetLine : HasIO io => (h : File) -> io (Either FileError String)
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fGetLine (FHandle f)
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= do res <- primIO (prim__readLine f)
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if prim__nullPtr res /= 0
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then returnError
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else ok (prim__getString res)
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||| Get a number of characters from the given file handle.
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||| @ h the file handle to read from
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||| @ max the number of characters to read
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export
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fGetChars : HasIO io => (h : File) -> (max : Int) -> io (Either FileError String)
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fGetChars (FHandle f) max
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= do res <- primIO (prim__readChars max f)
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if prim__nullPtr res /= 0
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then returnError
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else ok (prim__getString res)
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||| Get the next character from the given file handle.
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||| @ h the file handle to read from
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export
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fGetChar : HasIO io => (h : File) -> io (Either FileError Char)
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fGetChar h@(FHandle f)
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= do c <- primIO (prim__readChar f)
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ferr <- fileError h
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if ferr
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then returnError
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else ok (cast c)
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||| Write the given string to the file handle.
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||| @ h the file handle to write to
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||| @ str the string to write
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export
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fPutStr : HasIO io => (h : File) -> (str : String) -> io (Either FileError ())
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fPutStr (FHandle f) str
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= do res <- primIO (prim__writeLine f str)
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if res == 0
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then returnError
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else ok ()
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||| Write the given string, followed by a newline, to the file handle.
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|||
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||| @ fh the file handle to write to
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||| @ str the string to write
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export
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fPutStrLn : HasIO io => (fh : File) -> (str : String) -> io (Either FileError ())
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fPutStrLn fh str = fPutStr fh (str ++ "\n")
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||| Check whether the end-of-file indicator for the given file handle is set.
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||| @ h the file handle to check
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export
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fEOF : HasIO io => (h : File) -> io Bool
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fEOF (FHandle f)
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= do res <- primIO (prim__eof f)
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pure (res /= 0)
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||| Read all the remaining contents of a file handle
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export
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covering
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fRead : HasIO io => (h : File) -> io (Either FileError String)
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fRead h = fRead' h [<]
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where
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fRead' : HasIO io' => (h : File) -> (acc : SnocList String) -> io' (Either FileError String)
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fRead' h acc = do
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if !(fEOF h)
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then pure $ Right $ concat acc
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else do
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Right line <- fGetLine h
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| Left err => pure $ Left err
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fRead' h $ acc :< line
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||| Delete the file at the given name.
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||| @ fname the file to delete
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export
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removeFile : HasIO io => (fname : String) -> io (Either FileError ())
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removeFile fname
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= do res <- primIO (prim__removeFile fname)
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if res == 0
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then ok ()
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else returnError
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||| Read a number of lines into an accumulator, optionally starting at an offset
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||| in the given file handle. Requires `Fuel` to run since the operation is
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||| total but may run indefinitely; the functions `limit` and `forever` help
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||| with providing `Fuel`.
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||| On success, returns a tuple of whether the EOF was reached (if it wasn't, we
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||| ran out of fuel first) and the lines accumulated.
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||| Note: each line will still have a newline character at the end.
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||| @ acc the accumulator to read the lines onto
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||| @ offset the offset to start reading at
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||| @ fuel an amount of `Fuel`
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||| @ h the file handle to read from
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readLinesOnto : HasIO io => (acc : List String) ->
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(offset : Nat) ->
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(fuel : Fuel) ->
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(h : File) ->
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io (Either FileError (Bool, List String))
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readLinesOnto acc _ Dry h = pure (Right (False, reverse acc))
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readLinesOnto acc offset (More fuel) h
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= do False <- fEOF h
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| True => pure $ Right (True, reverse acc)
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case offset of
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(S offset') => (fSeekLine h *> readLinesOnto acc offset' (More fuel) h) @{Applicative.Compose}
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0 => (fGetLine h >>= \str => readLinesOnto (str :: acc) 0 fuel h) @{Monad.Compose}
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||| Read a chunk of a file in a line-delimited fashion.
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||| You can use this function to read an entire file
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||| as with @readFile@ by reading until @forever@ or by
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||| iterating through pages until hitting the end of
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||| the file.
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||| The @limit@ function can provide you with enough
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||| fuel to read exactly a given number of lines.
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||| On success, returns a tuple of whether the end of
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||| the file was reached or not and the lines read in
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||| from the file.
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||| Note that each line will still have a newline
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||| character at the end.
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||| Important: because we are chunking by lines, this
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||| function's totality depends on the assumption that
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||| no single line in the input file is infinite.
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||| @ offset the offset to start reading at
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||| @ until the `Fuel` limiting how far we can read
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||| @ fname the name of the file to read
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export
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readFilePage : HasIO io => (offset : Nat) -> (until : Fuel) -> (fname : String) ->
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io (Either FileError (Bool, List String))
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readFilePage offset fuel fname
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= withFile fname Read pure $
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readLinesOnto [] offset fuel
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||| Read the entire file at the given name. This function is `partial` since
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||| there is no guarantee that the given file isn't infinite.
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||| @ fname the name of the file to read
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export
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partial
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readFile : HasIO io => (fname : String) -> io (Either FileError String)
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readFile = (map $ map (fastConcat . snd)) . readFilePage 0 forever
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||| Write the given string to the file at the specified name. Opens the file
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||| with the `WriteTruncate` mode.
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||| (If you have a file handle (a `File`), you may be looking for `fPutStr`.)
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||| @ filePath the file to write to
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||| @ contents the string to write to the file
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export
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writeFile : HasIO io =>
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(filePath : String) -> (contents : String) ->
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io (Either FileError ())
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writeFile file contents
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= withFile file WriteTruncate pure $
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flip fPutStr contents
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||| Append the given string to the file at the specified name. Opens the file in
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||| with the `Append` mode.
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||| @ filePath the file to write to
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||| @ contents the string to write to the file
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export
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appendFile : HasIO io =>
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(filePath : String) -> (contents : String) ->
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io (Either FileError ())
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appendFile file contents
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= withFile file Append pure $
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flip fPutStr contents
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