Embed Directive in Racket

Here’s the translation of the Go embed directive example to Racket:

In Racket, we don’t have a direct equivalent to Go’s embed directive. However, we can achieve similar functionality using Racket’s built-in file operations and syntax extensions. Here’s how we can create a similar example:

#lang racket

(require racket/file)

; Define a macro to simulate the embed directive
(define-syntax-rule (embed-file filename)
  (file->string filename))

; Embed the contents of a single file into a string
(define file-string (embed-file "folder/single_file.txt"))

; Embed the contents of a single file into a byte string
(define file-byte (file->bytes "folder/single_file.txt"))

; Function to read multiple files from a folder
(define (read-folder pattern)
  (for/list ([file (in-list (find-files
                             (lambda (path)
                               (regexp-match? pattern path))
                             "folder"))])
    (cons (path->string file) (file->string file))))

; Embed multiple files using a pattern
(define folder (read-folder #rx".*\\.hash$"))

(define (main)
  ; Print out the contents of single_file.txt
  (displayln file-string)
  (displayln (bytes->string/utf-8 file-byte))
  
  ; Retrieve some files from the embedded folder
  (for ([file folder])
    (printf "~a: ~a\n" (car file) (cdr file))))

(main)

This Racket code simulates the functionality of Go’s embed directive:

1. We define a macro embed-file that reads the contents of a file into a string.

2. We use this macro to embed the contents of single_file.txt into both a string and a byte string.

3. We define a function read-folder that reads multiple files matching a pattern from a folder.

4. We use this function to read all .hash files from the folder directory.

5. In the main function, we print the contents of the embedded files.

To run this example, you would need to create the same folder structure and files as in the Go example:

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

Then you can run the Racket script:

$ racket embed-example.rkt
hello racket
hello racket
folder/file1.hash: 123
folder/file2.hash: 456

Note that Racket doesn’t have a built-in compile-time file embedding feature like Go’s embed directive. This example demonstrates how to achieve similar functionality at runtime. For more advanced use cases, you might want to look into Racket’s macro system or module system for compile-time file inclusion.