Execing Processes in Racket

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

Our example demonstrates how to replace the current process with another one using Racket’s equivalent of the classic exec function.

#lang racket

(require racket/system)

(define (main)
  ; For our example, we'll exec 'ls'. Racket doesn't require an
  ; absolute path, so we can use the command name directly.
  (define binary "ls")

  ; In Racket, we pass arguments as a list of strings.
  ; The first argument should be the program name.
  (define args '("ls" "-a" "-l" "-h"))

  ; Racket doesn't need to explicitly set environment variables
  ; for exec, as it uses the current environment by default.

  ; Here's the actual exec call. If this call is successful,
  ; the execution of our process will end here and be replaced
  ; by the 'ls -a -l -h' process.
  (process*/force binary args))

(main)

When we run our program, it is replaced by ls.

$ racket execing-processes.rkt
total 16K
drwxr-xr-x  2 user user 4.0K Jun 15 10:00 .
drwxr-xr-x 10 user user 4.0K Jun 15 09:59 ..
-rw-r--r--  1 user user  421 Jun 15 10:00 execing-processes.rkt

Note that Racket, like many high-level languages, doesn’t offer a classic Unix fork function. However, Racket provides other mechanisms for concurrent and parallel programming, such as threads and places, which cover most use cases for fork.

In this example, we used process*/force from the racket/system library, which is similar to exec in that it replaces the current process with a new one. However, unlike Unix exec, it does return control to the Racket program if the subprocess exits.

If you need more fine-grained control over process creation and management, Racket also provides functions like subprocess and system, which allow you to spawn processes without replacing the current one.