From c0f4fa031a208cd2723da07f2374c5e29710cc3f Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Mon, 19 Aug 2019 21:16:06 -0400
Subject: [PATCH 1/4] filter(f, tuple)

---
 base/tuple.jl | 15 +++++++++++++++
 test/tuple.jl |  9 +++++++++
 2 files changed, 24 insertions(+)

diff --git a/base/tuple.jl b/base/tuple.jl
index 7e8c6804bc496..2ff7f6ba1552a 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -249,6 +249,21 @@ _totuple(::Type{Tuple}, itr, s...) = (collect(Iterators.rest(itr,s...))...,)
 
 end
 
+## filter ##
+
+filter(f, t::Tuple) = _filter(f, t, ())
+function _filter(f, t::Tuple, r::Tuple)
+    @_inline_meta
+    if f(first(t))
+        _filter(f, tail(t), (r..., first(t)))
+    else
+        _filter(f, tail(t), r)
+    end
+end
+_filter(f, t::Tuple{}, r::Tuple) = r
+# use Array for long tuples
+filter(f, t::Any16) = Tuple(filter(f, collect(t)))
+
 ## comparison ##
 
 isequal(t1::Tuple, t2::Tuple) = (length(t1) == length(t2)) && _isequal(t1, t2)
diff --git a/test/tuple.jl b/test/tuple.jl
index 26d5d5f58d953..178aae69c4600 100644
--- a/test/tuple.jl
+++ b/test/tuple.jl
@@ -247,6 +247,15 @@ end
     @test_throws ArgumentError mapfoldl(abs, =>, ())
 end
 
+@testset "filter" begin
+    @test filter(isodd, (1,2,3)) == (1, 3)
+    @test filter(isequal(2), (true, 2.0, 3)) === (2.0,)
+    @test filter(i -> true, ()) == ()
+    @test filter(identity, (true,)) === (true,)
+    longtuple = ntuple(identity, 20)
+    @test filter(iseven, longtuple) == ntuple(i->2i, 10)
+end
+
 @testset "comparison and hash" begin
     @test isequal((), ())
     @test isequal((1,2,3), (1,2,3))

From bba183718e96df85bd701822eca187a98e3a7b2b Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 20 Aug 2019 00:07:38 -0400
Subject: [PATCH 2/4] one test

---
 base/tuple.jl | 4 ++--
 test/tuple.jl | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/base/tuple.jl b/base/tuple.jl
index 2ff7f6ba1552a..4de4683852577 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -255,9 +255,9 @@ filter(f, t::Tuple) = _filter(f, t, ())
 function _filter(f, t::Tuple, r::Tuple)
     @_inline_meta
     if f(first(t))
-        _filter(f, tail(t), (r..., first(t)))
+        return _filter(f, tail(t), (r..., first(t)))
     else
-        _filter(f, tail(t), r)
+        return _filter(f, tail(t), r)
     end
 end
 _filter(f, t::Tuple{}, r::Tuple) = r
diff --git a/test/tuple.jl b/test/tuple.jl
index 178aae69c4600..746fc297b1e9c 100644
--- a/test/tuple.jl
+++ b/test/tuple.jl
@@ -254,6 +254,7 @@ end
     @test filter(identity, (true,)) === (true,)
     longtuple = ntuple(identity, 20)
     @test filter(iseven, longtuple) == ntuple(i->2i, 10)
+    @test filter(x -> x<2, (longtuple..., 1.5)) === (1, 1.5)
 end
 
 @testset "comparison and hash" begin

From eac113af06b34a7edadde2a9401cfc8766e23aad Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Thu, 26 Sep 2019 16:09:34 +0200
Subject: [PATCH 3/4] afoldl magic one-line

Co-authored-by: Takafumi Arakaki <aka.tkf@gmail.com>
---
 base/tuple.jl | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/base/tuple.jl b/base/tuple.jl
index 4de4683852577..298c4d5246925 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -251,16 +251,8 @@ end
 
 ## filter ##
 
-filter(f, t::Tuple) = _filter(f, t, ())
-function _filter(f, t::Tuple, r::Tuple)
-    @_inline_meta
-    if f(first(t))
-        return _filter(f, tail(t), (r..., first(t)))
-    else
-        return _filter(f, tail(t), r)
-    end
-end
-_filter(f, t::Tuple{}, r::Tuple) = r
+filter(f, xs::Tuple) = afoldl((ys, x) -> f(x) ? (ys..., x) : ys, (), xs...)
+
 # use Array for long tuples
 filter(f, t::Any16) = Tuple(filter(f, collect(t)))
 

From d913e8009b555a8031c7065ff9e59c8fafebfe73 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Thu, 26 Sep 2019 16:17:09 +0200
Subject: [PATCH 4/4] add news, for 1.4

---
 NEWS.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/NEWS.md b/NEWS.md
index c09785c4f4f48..0ff86742a037d 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -24,6 +24,7 @@ New library functions
 Standard library changes
 ------------------------
 
+* `filter` can now act on a `Tuple` ([#32968]).
 
 #### Libdl