From f09e0d33a4d65ac71865ab83737b0c1c2f0d0eed Mon Sep 17 00:00:00 2001
From: Aryadev Chavali <aryadev@aryadevchavali.com>
Date: Wed, 11 Feb 2026 08:25:01 +0000
Subject: [PATCH] reader: deal with negative prefix numbers in read

---
 src/reader.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/reader.c b/src/reader.c
index 3588d96..ed0ec56 100644
--- a/src/reader.c
+++ b/src/reader.c
@@ -171,6 +171,25 @@ read_err_t read(sys_t *sys, stream_t *stream, lisp_t **ret)
   char c = stream_peek(stream);
   if (isdigit(c))
     return read_int(sys, stream, ret);
+  else if (c == '-')
+  {
+    char c1 = stream_next(stream);
+    if (isdigit(c1))
+    {
+      read_err_t err = read_int(sys, stream, ret);
+      if (err)
+        return err;
+      i64 n = as_int(*ret);
+      n *= -1;
+      *ret = make_int(n);
+      return READ_ERR_OK;
+    }
+    else if (is_sym(c1))
+    {
+      stream_seek_backward(stream, 1);
+      return read_sym(sys, stream, ret);
+    }
+  }
   else if (is_sym(c))
     return read_sym(sys, stream, ret);
   else if (c == '\'')