file

func Close ¶

func Close[C io.Closer](c C) IOEither[error, any]

Close closes an object

func Mkdir ¶

func Mkdir(path string, perm os.FileMode) IOEither[error, string]

Mkdir create a directory, see os.Mkdir

func MkdirAll ¶

func MkdirAll(path string, perm os.FileMode) IOEither[error, string]

MkdirAll create a sequence of directories, see os.MkdirAll

func ReadAll ¶

func ReadAll[R io.ReadCloser](acquire IOEither[error, R]) IOEither[error, []byte]

ReadAll uses a generator function to create a stream, reads it and closes it

func Remove ¶

func Remove(name string) IOEither[error, string]

Remove removes a file by name

func WithTempFile ¶

func WithTempFile[A any](f Kleisli[error, *os.File, A]) IOEither[error, A]

WithTempFile creates a temporary file, then invokes a callback to create a resource based on the file, then close and remove the temp file

func Read ¶

func Read[R any, RD io.ReadCloser](acquire IOEither[error, RD]) Kleisli[error, Kleisli[error, RD, R], R]

Read uses a generator function to create a stream, reads data from it using a provided reader function, and ensures the stream is properly closed after reading.

This function provides safe resource management for reading operations by:

1. Acquiring a ReadCloser resource using the provided acquire function
2. Applying a reader function to extract data from the resource
3. Ensuring the resource is closed, even if an error occurs during reading

Type Parameters:

• R: The type of data to be read from the stream
• RD: The type of the ReadCloser resource (must implement io.ReadCloser)

Parameters:

• acquire: An IOEither that produces the ReadCloser resource

Returns:

A Kleisli function that takes a reader function (which transforms RD to R)
and returns an IOEither that produces the read result R or an error.

Example:

import (
    "os"
    "io"
    F "github.com/IBM/fp-go/v2/function"
    "github.com/IBM/fp-go/v2/ioeither"
    "github.com/IBM/fp-go/v2/ioeither/file"
)

// Read first 10 bytes from a file
readFirst10 := func(f *os.File) ioeither.IOEither[error, []byte] {
    return ioeither.TryCatchError(func() ([]byte, error) {
        buf := make([]byte, 10)
        n, err := f.Read(buf)
        return buf[:n], err
    })
}

result := F.Pipe1(
    file.Open("data.txt"),
    file.Read[[]byte, *os.File],
)(readFirst10)

data, err := result()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Read: %s\n", data)

The Read function ensures that the file is closed even if the reading operation fails, providing safe and composable resource management in a functional style.

func Write ¶

func Write[R any, W io.WriteCloser](acquire IOEither[error, W]) Kleisli[error, Kleisli[error, W, R], R]

Write uses a generator function to create a stream, writes data to it and closes it

func WriteFile ¶

func WriteFile(dstName string, perm os.FileMode) Kleisli[error, []byte, []byte]

WriteFile writes a data blob to a file

func WriteAll ¶

func WriteAll[W io.WriteCloser](data []byte) Operator[error, W, []byte]

WriteAll uses a generator function to create a stream, writes data to it and closes it