Make a start on prerequisite data.

.gitignore

@@ -0,0 +1,2 @@
+scratch/
+/.dir-locals.el

modules/ordo/prerequisite-data.scm

@@ -0,0 +1,17 @@
+(define-module (ordo prerequisite-data)
+  #:use-module (oop goops))
+
+(define-class <prerequisite-data> ())
+
+(define-class <local-file> (<prerequisite-data>)
+  (path #:init-keyword #:path #:getter get-path))
+
+(define-method (equal? (x <local-file>) (y <local-file>))
+  (equal? (get-path x) (get-path y)))
+
+(define (local-file path)
+  (make <local-file> #:path path))
+
+(define-class <local-lookup> (<prerequisite-data>)
+  (handler #:init-keyword #:handler #:getter get-handler)
+  (args #:init-keyword #:args :getter get-args))

modules/ordo/util/filesystem.scm

@@ -34,6 +34,8 @@
 
 ;; This is based on reading guix/build/syscalls.scm but less general
 ;; than their implementation.
+;; TODO: why is this needed? The guile standard library has mkdtemp
+;; that seems to do the same thing.
 (define mkdtemp!
   (let* ((ptr (dynamic-func "mkdtemp" (dynamic-link)))
          (proc (pointer->procedure '* ptr '(*) #:return-errno? #t)))