Add an SML syntax test file.

tests/syntax-tests/source/SML/sample.sml

@@ -0,0 +1,47 @@
+val x = 0
+
+val hello = "hello world"
+
+val id = fn x => x
+
+fun id' x = x
+
+val () = print "hello world\n"
+
+val _ = let
+  val hello = "hello"
+  val world = "world"
+in
+  print (hello ^ " " ^ world ^ "\n")
+end
+
+fun isZero n =
+  if n = 0 then true
+  else false
+
+fun isTrue b =
+  case b of
+    true => true
+  | false => false
+
+exception Bad_value of string
+
+fun isTrue' b =
+  case b of
+    true => true
+  | _    => raise (Bad_value "value is not true!")
+
+val alwaysTrue =
+  isTrue' false handle Bad_value _ => true
+
+datatype myBool = True | False
+
+datatype shape = Square of real | Circle of real | Point
+
+signature FOO = sig
+  val foo : 'a -> 'a
+end
+
+structure Foo :> FOO = struct
+  fun foo x = x
+end