Embed Directive in Haskell

Here’s the translation of the Go code to Haskell, with explanations in Markdown format suitable for Hugo:

In Haskell, we don’t have a direct equivalent to Go’s embed directive. However, we can demonstrate file reading and handling, which is conceptually similar. We’ll use the readFile function from the System.IO module to read file contents.

First, let’s import the necessary modules:

import System.IO
import qualified Data.ByteString as BS

In Haskell, we don’t have global variables like in Go. Instead, we’ll define functions to read file contents:

readFileAsString :: FilePath -> IO String
readFileAsString = readFile

readFileAsByteString :: FilePath -> IO BS.ByteString
readFileAsByteString = BS.readFile

Now, let’s define our main function:

main :: IO ()
main = do
    -- Read and print the contents of 'single_file.txt'
    fileString <- readFileAsString "folder/single_file.txt"
    putStr fileString
    
    fileByte <- readFileAsByteString "folder/single_file.txt"
    BS.putStr fileByte
    
    -- Read and print contents of multiple files
    content1 <- readFileAsString "folder/file1.hash"
    putStr content1
    
    content2 <- readFileAsString "folder/file2.hash"
    putStr content2

To run this example, you would need to create the necessary files and folders:

$ mkdir -p folder
$ echo "hello haskell" > folder/single_file.txt
$ echo "123" > folder/file1.hash
$ echo "456" > folder/file2.hash

Then compile and run the Haskell program:

$ ghc embed-example.hs
$ ./embed-example
hello haskell
hello haskell
123
456

In this Haskell version, we’ve mimicked the behavior of Go’s embed directive by reading files at runtime. Haskell doesn’t have a built-in way to embed files at compile time like Go does, but it provides powerful file I/O capabilities that can be used to achieve similar results.

The readFileAsString function reads a file and returns its contents as a String, while readFileAsByteString reads a file and returns its contents as a ByteString (similar to Go’s []byte).

In the main function, we use these functions to read the contents of our files and print them out, mimicking the behavior of the original Go program.

While this approach doesn’t embed the files in the binary at compile time, it demonstrates how to handle file reading in Haskell, which is a common use case when working with external data.