From ad56659ca146fe51e65cda918677aab114940b87 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A5rd=20Rolstad=20Henriksen?=
 <bard.rolstad.henriksen@nrk.no>
Date: Fri, 6 Jul 2018 08:24:36 +0200
Subject: [PATCH] Add truncate as an alias to mimic Seq.

---
 src/FSharp.Control.AsyncSeq/AsyncSeq.fs              |  2 ++
 src/FSharp.Control.AsyncSeq/AsyncSeq.fsi             |  4 ++++
 tests/FSharp.Control.AsyncSeq.Tests/AsyncSeqTests.fs | 10 ++++++++++
 3 files changed, 16 insertions(+)

diff --git a/src/FSharp.Control.AsyncSeq/AsyncSeq.fs b/src/FSharp.Control.AsyncSeq/AsyncSeq.fs
index 5dc1fcb..b1b36f1 100644
--- a/src/FSharp.Control.AsyncSeq/AsyncSeq.fs
+++ b/src/FSharp.Control.AsyncSeq/AsyncSeq.fs
@@ -1286,6 +1286,8 @@ module AsyncSeq =
                   let! moven = ie.MoveNext()
                   b := moven
               else b := None }
+  
+  let truncate count source = take count source
 
   let skip count (source : AsyncSeq<'T>) : AsyncSeq<_> = asyncSeq {
       if (count < 0) then invalidArg "count" "must be non-negative"
diff --git a/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi b/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi
index d4f0f76..7734451 100644
--- a/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi
+++ b/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi
@@ -390,8 +390,12 @@ module AsyncSeq =
     val skipWhile : predicate:('T -> bool) -> source:AsyncSeq<'T> -> AsyncSeq<'T>
 
     /// Returns the first N elements of an asynchronous sequence
+    /// does not cast an exception if count is larger than the sequence length.
     val take : count:int -> source:AsyncSeq<'T> -> AsyncSeq<'T>
 
+    /// Alias for take
+    val truncate : count:int -> source:AsyncSeq<'T> -> AsyncSeq<'T>
+
     /// Skips the first N elements of an asynchronous sequence and
     /// then returns the rest of the sequence unmodified.
     val skip : count:int -> source:AsyncSeq<'T> -> AsyncSeq<'T>
diff --git a/tests/FSharp.Control.AsyncSeq.Tests/AsyncSeqTests.fs b/tests/FSharp.Control.AsyncSeq.Tests/AsyncSeqTests.fs
index a6bf097..03701cc 100644
--- a/tests/FSharp.Control.AsyncSeq.Tests/AsyncSeqTests.fs
+++ b/tests/FSharp.Control.AsyncSeq.Tests/AsyncSeqTests.fs
@@ -1388,6 +1388,16 @@ let ``AsyncSeq.take should work``() =
   let ls = ss |> AsyncSeq.toList
   ()
 
+[<Test>]
+let ``AsyncSeq.truncate should work like take``() =  
+  let s = asyncSeq {
+    yield ["a",1] |> Map.ofList
+  }
+  let expected = s |> AsyncSeq.take 1
+  let actual =  s |> AsyncSeq.truncate 1
+  Assert.AreEqual(expected, actual)
+
+
 [<Test>]
 let ``AsyncSeq.mapAsyncParallel should maintain order`` () =
   for i in 0..100 do