From d312b0598c17e0f2beb34b7d965015e64b765c6b Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Mon, 18 May 2020 19:11:11 -0400
Subject: [PATCH] WIP

---
 scheme/cyclone/transforms.sld | 3 +--
 scheme/cyclone/util.sld       | 1 +
 scheme/eval.sld               | 5 +++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/scheme/cyclone/transforms.sld b/scheme/cyclone/transforms.sld
index 0a6affb8..39e495c1 100644
--- a/scheme/cyclone/transforms.sld
+++ b/scheme/cyclone/transforms.sld
@@ -1001,10 +1001,9 @@ if (acc) {
             (not (assoc 'if renamed)))
        ;; Add a failsafe here in case macro expansion added more
        ;; incomplete if expressions.
-       ;; FUTURE: append the empty (unprinted) value instead of #f
        (let ((new-ast (if (if-else? ast)
                           `(if ,@(map (lambda (a) (convert a renamed)) (cdr ast)))
-                          (convert (append ast '(#f)) renamed))))
+                          (convert (append ast (list (void))) renamed))))
          (cond
           ;; Optimization - convert (if (not a) b c) into (if a c b)
           ((and (app? (if->condition new-ast))
diff --git a/scheme/cyclone/util.sld b/scheme/cyclone/util.sld
index dd7536ff..e16b93b8 100644
--- a/scheme/cyclone/util.sld
+++ b/scheme/cyclone/util.sld
@@ -172,6 +172,7 @@
   (or (integer? exp)
       (real? exp)
       (complex? exp)
+      (eq? (void) exp) ;; Poor man's (void?)
       (string? exp)
       (vector? exp)
       (bytevector? exp)
diff --git a/scheme/eval.sld b/scheme/eval.sld
index 42001ff6..acb5e95c 100644
--- a/scheme/eval.sld
+++ b/scheme/eval.sld
@@ -116,6 +116,7 @@
 (define (self-evaluating? exp)
   (cond ((number? exp) #t)
         ((boolean? exp) #t)
+        ((eq? (void) exp) #t) ;; Poor man's (void?)
         ((string? exp) #t)
         ((vector? exp) #t)
         ((bytevector? exp) #t)
@@ -159,7 +160,7 @@
 (define (if-alternative exp)
   (if (not (null? (cdddr exp))) ;; TODO: add (not) support
       (cadddr exp)
-      #f))
+      (void)))
 (define (make-if predicate consequent alternative)
   (list 'if predicate consequent alternative))
 
@@ -1022,7 +1023,7 @@
                                  ;; Insert default value for missing else clause
                                  ;; FUTURE: append the empty (unprinted) value
                                  ;; instead of #f
-                                 #f)))
+                                 (void))))
     ((define-c? exp) exp)
     ((define-syntax? exp)
      ;(trace:info `(define-syntax ,exp))