From 7b1e3ce5f77184488f58f9ed67dbc56bfc6d69e9 Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Mon, 24 Oct 2016 00:24:16 +0000
Subject: [PATCH] Issue #112: Allow reader to recognize inf and nan

---
 CHANGELOG.md    | 4 ++++
 scheme/read.sld | 9 ++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11d51f6e..b624d87f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 TODO: more performance improvements
 TODO: SRFI 113
 
+Features:
+
+- Allow the reader to recognize `+inf.0`, `-inf.0`, `+nan.0`, and `-nan.0`.
+
 Bug Fixes
 
 - Only throw a divide by zero error for integer division. Floating point divide by zero is allowed and evaluates to `nan`.
diff --git a/scheme/read.sld b/scheme/read.sld
index 51f3dbe6..3575b667 100644
--- a/scheme/read.sld
+++ b/scheme/read.sld
@@ -532,7 +532,14 @@
 (define (parse-atom a)
   (if (token-numeric? a)
       (string->number (list->string a))
-      (string->symbol (list->string a))))
+      (let ((atom (string->symbol (list->string a))))
+        (if (or (eq? atom '+inf.0)
+                (eq? atom '-inf.0))
+            (expt 2 1000000)
+            (if (or (eq? atom '+nan.0)
+                    (eq? atom '-nan.0))
+                (/ 0.0 0.0)
+                atom)))))
 
 ;;;;;
 ;; Read next character from port, using buffered char if available