From b809a26bb4606b127dfd5218e22cb93c5fe06254 Mon Sep 17 00:00:00 2001
From: hellerve <veit.heller@student.htw-berlin.de>
Date: Mon, 12 Sep 2016 17:56:36 +0200
Subject: [PATCH] initial

---
 README.md  | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 context.zp | 21 ++++++++++++++++++
 module.zp  | 12 +++++++++++
 3 files changed, 96 insertions(+)
 create mode 100644 README.md
 create mode 100644 context.zp
 create mode 100644 module.zp

diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,63 @@
+# context
+
+A context manager protocol for zepto.
+
+## Installation
+
+```
+zeps install hellerve/context
+```
+
+## Context Managers?
+
+Context managers provide the programmer with an easy way
+to work with resources that need management, i.e. explicit
+cleanup and/or deletion. Consider files for example: if
+we want to use them, we need to open them, work with them
+and the close them again. Context managers provide you with
+a context in which a file will be open, managing the closing
+itself when you are done.
+
+An example:
+```clojure
+; reading the first line of a file, without a context manager
+(define file (open-input-file "myfile.txt"))
+(write (read-line file))
+(close-input-file file)
+
+; the same, this time with a context manager
+(with (open-input-file "myfile.txt") file
+  (write (read-line file)))
+```
+
+## Usage
+
+The example above already showcases the most important function for
+users, `with`. It takes a value, a name to bind it to and a context
+in which this name should be defined.
+
+```clojure
+(with some-resource some-name
+  (do-something some-name)
+  (do-another-thing some-name))
+```
+
+The library also exposes a protocol `context-manager`, comprised of a
+function `teardown` which will clean a resource up after use.
+
+Use it like so:
+````clojure
+(defimpl context-manager my-resource?
+         ((teardown (lambda (resource)
+                      (begin
+                        (cleanup-my-resource resource)
+                        (delete-my-resource resource))))))
+```
+
+That's all, folks!
+
+This library comes bundled with a context manager for files and sockets.
+
+<hr/>
+
+Have fun!
diff --git a/context.zp b/context.zp
new file mode 100644
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+++ b/context.zp
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+(define-syntax with
+  (syntax-rules
+    "use a context manager. Takes a value, name and body
+     and binds value to name in body. Ensures resource cleanup.
+
+     params:
+      - val: the value to bind
+      - var: the name to bind to
+      - body: varargs for the body
+     complexity: O(1)
+     returns: the result of the resource cleanup"()
+    ((_ val var body ...)
+      (let ((var val))
+        (begin
+          body ...
+          (teardown var))))))
+
+(defprotocol context-manager ((teardown 1)))
+(defimpl context-manager input-port?  ((teardown close-input-file)))
+(defimpl context-manager output-port? ((teardown close-output-file)))
+(defimpl context-manager net:socket? ((teardown net:close-socket)))
diff --git a/module.zp b/module.zp
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+++ b/module.zp
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+#{:name "context"
+  :version "0.0.1"
+  :license "GPLv2"
+  :type :library
+  :tests []
+  :author #{:name "Veit Heller"
+            :email "veit@veitheller.de"
+            :github "@hellerve"}
+  :zepto #{:version "0.9.6"}
+  :dependencies ()
+  :dev-dependencies ()}
+