From ae7c062bdf4ab8337f0eedae78b38df24e62822c Mon Sep 17 00:00:00 2001
From: Eduardo Julian
Date: Thu, 30 Mar 2017 23:09:25 -0400
Subject: - Nat encoding/decoding is now implemented in the standard library.

---
 stdlib/source/lux.lux | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

(limited to 'stdlib/source/lux.lux')

diff --git a/stdlib/source/lux.lux b/stdlib/source/lux.lux
index fc606bc36..964cf5b57 100644
--- a/stdlib/source/lux.lux
+++ b/stdlib/source/lux.lux
@@ -1544,8 +1544,7 @@
   #Nil
   ($' Monad Maybe)
   {#wrap
-   (lambda' return [x]
-            (#Some x))
+   (lambda' [x] (#Some x))
    
    #bind
    (lambda' [f ma]
@@ -2070,10 +2069,32 @@
   (-> Bool Text)
   (if x "true" "false"))
 
-(def:''' (Nat/encode x)
+(def:''' (digit-to-text digit)
   #Nil
   (-> Nat Text)
-  (_lux_proc ["nat" "encode"] [x]))
+  (_lux_case digit
+    +0 "0"
+    +1 "1" +2 "2" +3 "3"
+    +4 "4" +5 "5" +6 "6"
+    +7 "7" +8 "8" +9 "9"
+    _ (_lux_proc ["io" "error"] ["undefined"])))
+
+(def:''' (Nat/encode value)
+  #Nil
+  (-> Nat Text)
+  (_lux_case value
+    +0
+    "+0"
+
+    _
+    (let' [loop (_lux_: (-> Nat Text Text)
+                  (lambda' recur [input output]
+                           (if (_lux_proc ["nat" "="] [input +0])
+                             (_lux_proc ["text" "append"] ["+" output])
+                             (recur (_lux_proc ["nat" "/"] [input +10])
+                                    (_lux_proc ["text" "append"] [(digit-to-text (_lux_proc ["nat" "%"] [input +10]))
+                                                                  output])))))]
+          (loop value ""))))
 
 (def:''' (Int/encode x)
   #Nil
-- 
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