record update syntax

tests/RUTest.newt

@@ -0,0 +1,19 @@
+module RUTest
+
+import Prelude
+
+record Foo where
+  constructor MkFoo
+  bar : Nat
+  baz : Nat
+
+blah : Foo → Foo
+blah x = [ bar := Z ] x
+
+main : IO Unit
+main = do
+  let x = blah $ MkFoo (S Z) (S (S Z))
+  printLn x.bar
+  -- this is unfortunate, it can't get record type from a meta
+  let x' = the Foo $ [ baz := Z ] x
+  printLn x'.baz