IOError

The IOError type provides structured error handling for file and I/O operations. Used by File module functions like File.read, File.write, File.append, and File.delete.

import IO

match File.read "config.txt"
  | Ok content -> process content
  | Err FileNotFound{path} -> println "File not found: ${path}"
  | Err AccessDenied{path} -> println "Access denied: ${path}"
  | Err e -> println "Error: ${Error.message e}"

Constructors

IOError

type IOError = FileNotFound{...} | AccessDenied{...} | ...

Constructor	Fields	Description
`FileNotFound`	`path: String`	The specified file does not exist
`AccessDenied`	`path: String`	Permission denied for the operation
`IsDirectory`	`path: String`	Expected a file but found a directory
`NotDirectory`	`path: String`	Expected a directory but found a file
`ReadError`	`message: String`	Error while reading
`WriteError`	`message: String`	Error while writing
`DeleteError`	`message: String`	Error while deleting
`OutOfMemory`	—	Insufficient memory for operation
`IOError`	`message: String`	Generic I/O error

Trait Implementations

Show

Provides human-readable error descriptions:

err = FileNotFound{path: "/tmp/missing.txt"}
println (show err)
# => FileNotFound: /tmp/missing.txt

Error

Implements the standard Error trait with message and kind:

Constructor	Error Kind
`FileNotFound`	`:file-not-found`
`AccessDenied`	`:access-denied`
`IsDirectory`	`:is-directory`
`NotDirectory`	`:not-directory`
`ReadError`	`:read-error`
`WriteError`	`:write-error`
`DeleteError`	`:delete-error`
`OutOfMemory`	`:out-of-memory`
`IOError`	`:io-error`

Examples

Reading a File with Error Handling

read-config = fn(path) =>
  match File.read path
    | Ok content -> Ok (parse-config content)
    | Err FileNotFound{..} -> Ok default-config
    | Err AccessDenied{path} ->
      println "Warning: Cannot read ${path}, using defaults"
      Ok default-config
    | Err e -> Err e

Handling by Error Kind

handle-error = fn(err) =>
  match Error.kind err
    | :file-not-found -> println "File missing"
    | :access-denied -> println "Permission denied"
    | _ -> println "I/O error: ${Error.message err}"