From 69c97a55124d618c9c3b4607c49cba6b524dc05a Mon Sep 17 00:00:00 2001
From: Stephen Chang <stchang@ccs.neu.edu>
Date: Tue, 11 Nov 2014 18:21:43 -0500
Subject: [PATCH] start tapl/ dir

---
 tapl/stlc-tests.rkt |  1 +
 tapl/stlc.rkt       | 17 +++++++++++++++++
 tapl/typecheck.rkt  |  3 +++
 3 files changed, 21 insertions(+)
 create mode 100644 tapl/stlc-tests.rkt
 create mode 100644 tapl/stlc.rkt
 create mode 100644 tapl/typecheck.rkt

diff --git a/tapl/stlc-tests.rkt b/tapl/stlc-tests.rkt
new file mode 100644
index 0000000..5bc0523
--- /dev/null
+++ b/tapl/stlc-tests.rkt
@@ -0,0 +1 @@
+#lang s-exp "stlc.rkt"
\ No newline at end of file
diff --git a/tapl/stlc.rkt b/tapl/stlc.rkt
new file mode 100644
index 0000000..0797d60
--- /dev/null
+++ b/tapl/stlc.rkt
@@ -0,0 +1,17 @@
+#lang racket/base
+(require
+  (for-syntax racket/base syntax/parse))
+  
+;; Simply-Typed Lambda Calculus
+;; - one arg lambda
+;; - var
+;; - binary app
+;; - binary +
+;; - integers
+
+(define-syntax (datum/tc stx)
+  (syntax-parse stx
+    [(_ . n:integer) (⊢ (syntax/loc stx (#%datum . n)) #'Int)]
+    [(_ . x)
+     #:when (type-error #:src #'x #:msg "Literal ~a has unknown type." #'x)
+     (syntax/loc stx (#%datum . x))]))
\ No newline at end of file
diff --git a/tapl/typecheck.rkt b/tapl/typecheck.rkt
new file mode 100644
index 0000000..832066e
--- /dev/null
+++ b/tapl/typecheck.rkt
@@ -0,0 +1,3 @@
+#lang racket/base
+
+;; general type checking utility functions
\ No newline at end of file