From 215a272cf2521c34e9f8d2be62db1a35ac0a9809 Mon Sep 17 00:00:00 2001
From: Tim Vaughan <tgvaughan@gmail.com>
Date: Mon, 25 Jul 2016 23:04:23 +1200
Subject: [PATCH] Fixed TCO bug.

---
 defer-is.4th |  7 ++-----
 scheme.4th   | 17 ++++++++---------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/defer-is.4th b/defer-is.4th
index 3949d0c..ac82c90 100644
--- a/defer-is.4th
+++ b/defer-is.4th
@@ -37,8 +37,5 @@ hide abort-defer
 
 \ Need this for tail call optimization
 
-: goto ( cfa -- )
-    R> drop execute ;
-
-: goto-prime ( cfa -- )
-    R> R> 2drop execute ;
+: goto-deferred ( cfa -- )
+    R> drop >body @ >body >R ;
diff --git a/scheme.4th b/scheme.4th
index 1f2111a..8bc44d3 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -3,6 +3,11 @@ scheme definitions
 
 include term-colours.4th
 include defer-is.4th
+include catch-throw.4th
+
+defer read
+defer eval
+defer print
 
 \ ------ Types ------
 
@@ -376,8 +381,6 @@ include scheme-primitives.4th
 
 \ ---- Read ---- {{{
 
-defer read
-
 variable parse-idx
 variable stored-parse-idx
 create parse-str 161 allot
@@ -785,8 +788,6 @@ parse-idx-stack parse-idx-sp !
 
 \ ---- Eval ---- {{{
 
-defer eval
-
 : self-evaluating? ( obj -- obj bool )
     boolean-type istype? if true exit then
     fixnum-type istype? if true exit then
@@ -981,8 +982,7 @@ defer eval
                 2drop ( env body )
                 car 2swap ( exp env )
 
-                ['] eval goto-prime  \ Tail call optimization
-                \ eval               \ No tail call optimization
+                R> drop ['] eval goto-deferred  \ Tail call optimization
             endof
 
             bold fg red ." Object not applicable. Aboring." reset-term cr
@@ -1030,7 +1030,8 @@ defer eval
             if-alternative
         then
 
-        2swap ['] eval goto
+        2swap
+        ['] eval goto-deferred
     then
 
     lambda? if
@@ -1058,8 +1059,6 @@ defer eval
 
 \ ---- Print ---- {{{
 
-defer print
-
 : printnum ( numobj -- ) drop 0 .R ;
 
 : printbool ( numobj -- )
-- 
2.20.1