Even More Scripting With Racket

Extending my use of racket to allow my shell scripts to be parameterized.

Lately for various reasons, I’ve been trying to move stuff off of my C drive. As with most of us the C drive has become a bit of a chokepoint for me in terms of free space. So I’ve had an external drive for a while (E:) and lately as I add stuff I’ve been shifting it over to my E: drive.

Some of you may recall that I was using Racket within Powershell to automate things. So here’s an update on that idea with some comments afterward.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

; e:/usr/bin/Racket/Racket.exe (Resolve-Path $PSCommandPath) $args
; Exit

#lang typed/racket/base
(require typed/racket)

(define no-args-passed "")
(define command-line-empty? (= (vector-length (current-command-line-arguments)) 0))

(: first-arg String)
(define first-arg (if (not command-line-empty?) (vector-ref (current-command-line-arguments) 0) no-args-passed))

(: DEFAULT-ZED-SOURCE-PATH String)
(define DEFAULT-ZED-SOURCE-PATH "E:\\zed")

(: zed-source-path String)
(define zed-source-path (if (string=? first-arg no-args-passed) DEFAULT-ZED-SOURCE-PATH first-arg))

(: ZED-GIT-DIR Path)
(define ZED-GIT-DIR (string->path zed-source-path))

(: ZED-UPDATE-CMD String)
(define ZED-UPDATE-CMD "git pull origin main")

(parameterize ((current-directory ZED-GIT-DIR)) (system ZED-UPDATE-CMD))

As you might guess I created a script to automate pulling down the most recent Zed source code. However I initially had it on my C:. So I modified my zup.ps1 script to allow me to pull the source to E or to specify a different location. I can pass a directory on the command line but if I don’t it’s defaulted to DEFAULT-ZED-SOURCE-PATH. The current-command-line-arguments parameter (and the word “parameter” has a very specific meaning in Racket by the way) is set by Racket when I invoke the zup.ps1 script. If I pass something on the command line it goes into the current-command-line-arguments parameter. So further down where I define zed-path I check if no arguments were passed and if not I default to my E drive.

EDIT: It was pointed out to me by one of the knowledgeable Racket folks that Racket has a very nice library for dealing with command lines. I thought about using it but in this case since I’m only dealing with one unnamed parameter it just seemed like it would be overengineering a solution.