From a492ea820c681136b5445f248a810f6f648a5baa Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Tue, 15 Aug 2017 13:23:16 +0000
Subject: [PATCH] Handle datum comments

---
 read.scm  | 3 +++
 runtime.c | 6 ++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/read.scm b/read.scm
index 9d04b907..84642e0b 100644
--- a/read.scm
+++ b/read.scm
@@ -777,6 +777,9 @@
        (list 'unquote (parse2 fp)))
       ((eq? token (string->symbol ",@"))
        (list 'unquote-splicing (parse2 fp)))
+      ((eq? token (string->symbol "#;"))
+       (parse2 fp) ;; Ignore next datum
+       (parse2 fp))
       ;; Other special cases?
       (else
         token))))
diff --git a/runtime.c b/runtime.c
index a573b072..1b5f778d 100644
--- a/runtime.c
+++ b/runtime.c
@@ -5995,10 +5995,12 @@ void Cyc_io_read_token(void *data, object cont, object port)
       _read_next_char(data, cont, p); // Fill buffer
       c = p->mem_buf[p->buf_idx++];
       p->col_num++;
-      // TODO: block comment
-      if (c == '|') {
+      if (c == '|') { // Block comment
         _read_multiline_comment(p);
         continue;
+      } else if (c == ';') { // Datum comment
+        object sym = find_or_add_symbol("#;");
+        return_thread_runnable(data, sym);
       } else if (c == 't') {
         if ((p->mem_buf_len - p->buf_idx) >= 3 &&
             p->mem_buf[p->buf_idx + 0] == 'r' &&