From 25750ee505bd976d3c606200fec7253ad40c46d9 Mon Sep 17 00:00:00 2001
From: Rose Hogenson <rhogenson@posteo.net>
Date: Mon, 1 Aug 2022 19:37:49 -0700
Subject: Remove mutable globals.

Per a closer reading of R7RS, it's an error to mutate an imported
binding with set!. My apologies to Guile when I said they had a bug.
---
 csc.csc              |  4 ++--
 lib/csc/compiler.csc |  6 +++++-
 lib/csc/flag.csc     | 13 +++++++------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/csc.csc b/csc.csc
index 9dae75f..c338aa7 100644
--- a/csc.csc
+++ b/csc.csc
@@ -4,7 +4,7 @@
         (only (scheme read)
           read)
         (only (csc compiler)
-          *library-search-dirs*
+          add-library-search-dirs
           compile)
         (only (csc flag)
           *args*
@@ -69,7 +69,7 @@
                        ((file) file)
                        (_ (printf "Error: must pass exactly one file to csc.\n{}" *help-msg*)
                           (exit 2))))
-  (set! *library-search-dirs* *include*)
+  (add-library-search-dirs *include*)
   (write-file *output* (compile (read-file input-file))))
 
 
diff --git a/lib/csc/compiler.csc b/lib/csc/compiler.csc
index 20d5d37..7054f10 100644
--- a/lib/csc/compiler.csc
+++ b/lib/csc/compiler.csc
@@ -1,6 +1,6 @@
 (define-library (csc compiler)
   (export
-    *library-search-dirs*
+    add-library-search-dirs
     compile)
   (import (scheme base)
           (only (scheme file)
@@ -88,6 +88,10 @@
     (define *library-search-dirs* '())
 
 
+    (define (add-library-search-dirs ds)
+      (set! *library-search-dirs* (append *library-search-dirs* ds)))
+
+
     (define (find-library name)
       (define library-roots (cons *standard-library-dir* *library-search-dirs*))
       (loop for dir in library-roots
diff --git a/lib/csc/flag.csc b/lib/csc/flag.csc
index c0a28a8..c26fa90 100644
--- a/lib/csc/flag.csc
+++ b/lib/csc/flag.csc
@@ -38,9 +38,11 @@
 
 
     (define *parsers* (make-map compare-strings))
-    ; I'm working around a Guile bug, which wrongly concludes
-    ; that *parsers* is immutable.
-    (set! *parsers* *parsers*)
+
+
+    (define (add-parser flag bool? setter)
+      (set! *parsers* (insert *parsers* flag
+                        (make-flag bool? setter))))
 
 
     (define-record-type <flag>
@@ -55,9 +57,8 @@
         ((define-flag name flag type default)
           (begin
             (define name default)
-            (set! *parsers* (insert *parsers* flag
-                              (make-flag (eq? type bool-flag)
-                                         (lambda (x) (set! name (type x))))))))))
+            (add-parser flag (eq? type bool-flag)
+                        (lambda (x) (set! name (type x))))))))
 
 
     (define *args* '())
-- 
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