Add createAndExercise to the standard library (#3182)

compiler/damlc/daml-stdlib-src/DA/Internal/Template.daml

@@ -110,6 +110,12 @@ exerciseByKey k c = do
     (cid, _) <- fetchByKey @t k
     exercise cid c
 
+-- | Create a contract and exercise the choice on the newly created contract.
+createAndExercise : forall t k c r. Choice t c r => t -> c -> Update r
+createAndExercise t c = do
+    cid <- create t
+    exercise cid c
+
 data NonConsuming t = NonConsuming {}
 data PreConsuming t = PreConsuming {}
 data PostConsuming t = PostConsuming {}

compiler/damlc/tests/daml-test-files/CreateAndExercise.daml

@@ -0,0 +1,20 @@
+-- Copyright (c) 2019, Digital Asset (Switzerland) GmbH and/or its affiliates.
+-- All rights reserved.
+
+daml 1.2 module CreateAndExercise where
+
+import DA.Assert
+
+template T1
+  with
+    p : Party
+  where
+    signatory p
+    choice C1 : Int
+      controller p
+      do pure 42
+
+main = scenario do
+  alice <- getParty "Alice"
+  r <- alice `submit` createAndExercise (T1 alice) C1
+  r === 42

unreleased.rst

@@ -34,3 +34,4 @@ HEAD — ongoing
    - `com.digitalasset.daml-lf-archive` becomes `com.digitalasset:daml-lf-dev-archive-java-proto`
    - `com.digitalasset.daml-lf-archive-scala` becomes `com.digitalasset.daml-lf-archive-reader`
 -[Sandbox] Filter contracts or contracts keys in the database query for parties that cannot see them.
++ [DAML Standard Library] Add ``createAndExercise``