From a6dbf20faf95ae892a805b8e83c131a4733f564f Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Tue, 15 Mar 2016 19:10:06 +0100
Subject: Implement simple number guessing game example

---
 README.md         |  2 ++
 example/guess.scm | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 example/guess.scm

diff --git a/README.md b/README.md
index 15b1253..0f709a2 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,8 @@ The only non-API wrapper provided by this library is `pollUpdates` which enables
 
 `example/echo.scm` implements a bot that echoes all messages back to their sender.
 
+`example/guess.scm` implements a simple number guessing game.
+
 ## Dependencies
 
 * [openssl](http://wiki.call-cc.org/eggref/4/openssl)
diff --git a/example/guess.scm b/example/guess.scm
new file mode 100644
index 0000000..c3267ff
--- /dev/null
+++ b/example/guess.scm
@@ -0,0 +1,59 @@
+(require-extension telebot
+                   (prefix telebot telebot:))
+
+(use srfi-69)
+(use extras)
+(use data-structures)
+
+(define (resolve-query query tree)
+  (fold (lambda (x y) (alist-ref x y))
+        tree
+        query))
+
+(define token (car (command-line-arguments)))
+(define conversations (make-hash-table))
+
+(define (send chat_id text)
+  (telebot:sendMessage token
+                       chat_id: chat_id
+                       text:    text))
+
+(define (print-failed-guess chat_id answer guess)
+  (print "User " chat_id " guessed " guess " instead of " answer))
+
+(define (make-conversation chat_id)
+  (let ((chat_id   chat_id)
+        (answer    (random 100)))
+    (lambda (text)
+      (let ((guess (string->number text)))
+        (if (equal? #f guess)
+          (send chat_id
+                "This is not a number - please provide your guess in base 10.")
+          (cond ((= guess answer)
+                 (begin (send chat_id
+                              "Correct! Feel free to guess the next number.")
+                        (print "User " chat_id " correctly guessed " answer)
+                        (set! answer (random 100))))
+                ((< guess answer)
+                 (begin (send chat_id
+                              "Too small. Try again.")
+                        (print-failed-guess chat_id answer guess)))
+                ((> guess answer)
+                 (begin (send chat_id
+                              "Too large. Try again.")
+                        (print-failed-guess chat_id answer guess)))))))))
+
+(define (handle-message m)
+  (let ((chat_id (resolve-query '(message from id) m))
+        (text    (resolve-query '(message text)    m)))
+    (if (hash-table-exists? conversations chat_id)
+      ((hash-table-ref conversations chat_id) text)
+      (begin (hash-table-set! conversations chat_id (make-conversation chat_id))
+             (print "Started talking to user " chat_id)
+             (send chat_id
+                   "Hi there! I just generated a random number for you to guess!")))))
+
+(randomize)
+(telebot:pollUpdates token
+                     (lambda (u) (if (telebot:is-message? u)
+                                   (handle-message u))))
-- 
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