From 8250705ecb182f9ea0da4b4dacd79350eee68791 Mon Sep 17 00:00:00 2001
From: ben <benjaminlgreenman@gmail.com>
Date: Tue, 8 Mar 2016 11:59:55 -0500
Subject: [PATCH] [icfp] note: typed/racket db imports

---
 icfp-2016/implementation.scrbl | 40 ++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/icfp-2016/implementation.scrbl b/icfp-2016/implementation.scrbl
index f8b7683..ddd781e 100644
--- a/icfp-2016/implementation.scrbl
+++ b/icfp-2016/implementation.scrbl
@@ -15,6 +15,46 @@
 
 
 
+@section{Database}
+
+Note: Typed Racket users can already specialize functions from the @tt{db} library
+ by giving them exact types in an import statement:
+
+@racketblock[
+  (require/typed db
+    (#:opaque Connection connection?)
+    (postgresql-connect (->* () (#:user String #:database String) Connection))
+    (query-row (-> Connection String Any * (Vector Natural String)))
+    (query-maybe-row (-> Connection String Any * (Option (Vector Natural String))))
+    ....)
+]
+
+The above statement asserts that @racket[query-row] only returns rows containing
+ a natural number followed by a string.
+To work with multiple tables in the same module, a programmer can re-import
+ @racket[db] functions using a different name and type.
+
+@todo{cohernet table names}
+@racketblock[
+  (require/typed (prefix-in w: db)
+    (w:query-row (-> Connection String Any * (Vector Natural String))))
+
+  (require/typed (prefix-in s: db)
+    (s:query-row (-> Connection String Any * (Vector Natural Natural))))
+]
+
+@todo{Other languages? also follow this approach}
+
+The benefits of our approach are:
+@itemlist[
+  @item{
+    Single point of control for database types, instead of spreading types
+    across identifiers in the @racket[require/typed] statement.
+  }
+  @item{
+    Compile-time validation of query strings.
+  }
+]