From 88f59d07a1a891d8dc180b9fb197b75533fe40f1 Mon Sep 17 00:00:00 2001
From: Joel Martin <github@martintribe.org>
Date: Tue, 25 Mar 2014 15:15:32 -0700
Subject: Postscript: step0_repl.ps

Run it using ghostscript:

    gs -q -dNODISPLAY step0_repl.ps
---
 ps/step0_repl.ps | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 ps/step0_repl.ps

diff --git a/ps/step0_repl.ps b/ps/step0_repl.ps
new file mode 100644
index 0000000..3aade39
--- /dev/null
+++ b/ps/step0_repl.ps
@@ -0,0 +1,44 @@
+% read
+/READ {
+    % just "return" the input string
+    /str exch def
+    str
+} def
+
+
+% eval
+/EVAL {
+    % just "return" the "ast"
+    /env exch def
+    /ast exch def
+    ast
+} def
+
+
+% print
+/PRINT {
+    % just "return" the expression
+    /exp exch def
+    exp
+} def
+
+
+% repl
+/REP {
+    READ (stub env) EVAL PRINT
+} def
+
+{ % loop
+    (user> ) print flush
+
+    %(%lineedit) (r) file 99 string readline
+    (%stdin) (r) file 99 string readline
+
+    not { exit } if  % exit if EOF
+
+    %(\ngot line: ) print dup print (\n) print flush
+    REP print (\n) print
+} bind loop
+
+(\n) print  % final newline before exit for cleanliness
+quit
-- 
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