From b09da6739019950fcdf0aa4a6757d545fc1f494c Mon Sep 17 00:00:00 2001
From: Ron Buckton <ron.buckton@microsoft.com>
Date: Sat, 7 Oct 2017 14:46:33 -0700
Subject: [PATCH] Added tests for pipeline

---
 src/compiler/checker.ts                       |  2 +-
 .../emitter.pipelineOperatorStage1.es2015.js  | 13 ++++
 ...tter.pipelineOperatorStage1.es2015.symbols | 40 ++++++++++++
 ...mitter.pipelineOperatorStage1.es2015.types | 48 ++++++++++++++
 .../emitter.pipelineOperatorStage1.es5.js     | 13 ++++
 ...emitter.pipelineOperatorStage1.es5.symbols | 40 ++++++++++++
 .../emitter.pipelineOperatorStage1.es5.types  | 48 ++++++++++++++
 .../emitter.pipelineOperatorStage1.esnext.js  | 12 ++++
 ...tter.pipelineOperatorStage1.esnext.symbols | 40 ++++++++++++
 ...mitter.pipelineOperatorStage1.esnext.types | 48 ++++++++++++++
 .../reference/pipelineOperatorStage1.js       | 13 ++++
 .../reference/pipelineOperatorStage1.symbols  | 49 +++++++++++++++
 .../reference/pipelineOperatorStage1.types    | 63 +++++++++++++++++++
 ...peratorStage1WithNonFunctionRHS.errors.txt | 14 +++++
 ...ipelineOperatorStage1WithNonFunctionRHS.js | 12 ++++
 ...neOperatorStage1WithNonFunctionRHS.symbols | 37 +++++++++++
 ...lineOperatorStage1WithNonFunctionRHS.types | 39 ++++++++++++
 .../emitter.pipelineOperatorStage1.es2015.ts  |  8 +++
 .../emitter.pipelineOperatorStage1.es5.ts     |  9 +++
 .../emitter.pipelineOperatorStage1.esnext.ts  |  8 +++
 .../pipelineOperatorStage1.ts                 |  9 +++
 ...ipelineOperatorStage1WithNonFunctionRHS.ts |  8 +++
 22 files changed, 572 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.js
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.symbols
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.types
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.es5.js
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.es5.symbols
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.es5.types
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.js
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.symbols
 create mode 100644 tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.types
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1.js
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1.symbols
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1.types
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.errors.txt
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.js
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.symbols
 create mode 100644 tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.types
 create mode 100644 tests/cases/conformance/emitter/es2015/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es2015.ts
 create mode 100644 tests/cases/conformance/emitter/es5/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es5.ts
 create mode 100644 tests/cases/conformance/emitter/esnext/pipelineOperatorStage1/emitter.pipelineOperatorStage1.esnext.ts
 create mode 100644 tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1.ts
 create mode 100644 tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 9e932c3017a..9db800caa06 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -25337,7 +25337,7 @@ namespace ts {
         }
 
         function checkGrammarPipelineExpression(node: PipelineExpression) {
-            if (!compilerOptions.experimentalPipeline) {
+            if (!compilerOptions.experimentalPipelineStage1) {
                 return grammarErrorOnNode(node.operatorToken, Diagnostics.Pipeline_expressions_are_part_of_a_stage_1_ECMAScript_proposal_and_are_subject_to_change_in_future_releases_Set_the_experimentalPipelineStage1_option_to_remove_this_warning);
             }
         }
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.js b/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.js
new file mode 100644
index 00000000000..0424cb367c7
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.js
@@ -0,0 +1,13 @@
+//// [emitter.pipelineOperatorStage1.es2015.ts]
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function identity<T>(value: T): T;
+
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
+
+
+//// [emitter.pipelineOperatorStage1.es2015.js]
+const x = (_a = ar, (_ => map(_, x => x + 1))(_a));
+const y = (_b = ar, identity(_b));
+var _a, _b;
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.symbols b/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.symbols
new file mode 100644
index 00000000000..f959933903e
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.symbols
@@ -0,0 +1,40 @@
+=== tests/cases/conformance/emitter/es2015/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es2015.ts ===
+declare const ar: Iterable<number>;
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es2015.ts, 0, 13))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : Symbol(map, Decl(emitter.pipelineOperatorStage1.es2015.ts, 0, 35))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 21))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 23))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 21))
+>fn : Symbol(fn, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 43))
+>v : Symbol(v, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 49))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 21))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 23))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 23))
+
+declare function identity<T>(value: T): T;
+>identity : Symbol(identity, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 74))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es2015.ts, 2, 26))
+>value : Symbol(value, Decl(emitter.pipelineOperatorStage1.es2015.ts, 2, 29))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es2015.ts, 2, 26))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es2015.ts, 2, 26))
+
+const x = ar |> (_ => map(_, x => x + 1));
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.es2015.ts, 4, 5))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es2015.ts, 0, 13))
+>_ : Symbol(_, Decl(emitter.pipelineOperatorStage1.es2015.ts, 4, 17))
+>map : Symbol(map, Decl(emitter.pipelineOperatorStage1.es2015.ts, 0, 35))
+>_ : Symbol(_, Decl(emitter.pipelineOperatorStage1.es2015.ts, 4, 17))
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.es2015.ts, 4, 28))
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.es2015.ts, 4, 28))
+
+const y = ar |> identity;
+>y : Symbol(y, Decl(emitter.pipelineOperatorStage1.es2015.ts, 5, 5))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es2015.ts, 0, 13))
+>identity : Symbol(identity, Decl(emitter.pipelineOperatorStage1.es2015.ts, 1, 74))
+
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.types b/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.types
new file mode 100644
index 00000000000..2c6d4e8d1b9
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.es2015.types
@@ -0,0 +1,48 @@
+=== tests/cases/conformance/emitter/es2015/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es2015.ts ===
+declare const ar: Iterable<number>;
+>ar : Iterable<number>
+>Iterable : Iterable<T>
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>T : T
+>U : U
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => U
+>v : T
+>T : T
+>U : U
+>Iterable : Iterable<T>
+>U : U
+
+declare function identity<T>(value: T): T;
+>identity : <T>(value: T) => T
+>T : T
+>value : T
+>T : T
+>T : T
+
+const x = ar |> (_ => map(_, x => x + 1));
+>x : Iterable<number>
+>ar |> (_ => map(_, x => x + 1)) : Iterable<number>
+>ar : Iterable<number>
+>(_ => map(_, x => x + 1)) : (_: Iterable<number>) => Iterable<number>
+>_ => map(_, x => x + 1) : (_: Iterable<number>) => Iterable<number>
+>_ : Iterable<number>
+>map(_, x => x + 1) : Iterable<number>
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>_ : Iterable<number>
+>x => x + 1 : (x: number) => number
+>x : number
+>x + 1 : number
+>x : number
+>1 : 1
+
+const y = ar |> identity;
+>y : Iterable<number>
+>ar |> identity : Iterable<number>
+>ar : Iterable<number>
+>identity : <T>(value: T) => T
+
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.js b/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.js
new file mode 100644
index 00000000000..637abb6b3ad
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.js
@@ -0,0 +1,13 @@
+//// [emitter.pipelineOperatorStage1.es5.ts]
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function identity<T>(value: T): T;
+
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
+
+
+//// [emitter.pipelineOperatorStage1.es5.js]
+var x = (_a = ar, (function (_) { return map(_, function (x) { return x + 1; }); })(_a));
+var y = (_b = ar, identity(_b));
+var _a, _b;
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.symbols b/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.symbols
new file mode 100644
index 00000000000..7d43eecf77f
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.symbols
@@ -0,0 +1,40 @@
+=== tests/cases/conformance/emitter/es5/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es5.ts ===
+declare const ar: Iterable<number>;
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es5.ts, 0, 13))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : Symbol(map, Decl(emitter.pipelineOperatorStage1.es5.ts, 0, 35))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 21))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 23))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 21))
+>fn : Symbol(fn, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 43))
+>v : Symbol(v, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 49))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 21))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 23))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 23))
+
+declare function identity<T>(value: T): T;
+>identity : Symbol(identity, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 74))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es5.ts, 2, 26))
+>value : Symbol(value, Decl(emitter.pipelineOperatorStage1.es5.ts, 2, 29))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es5.ts, 2, 26))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.es5.ts, 2, 26))
+
+const x = ar |> (_ => map(_, x => x + 1));
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.es5.ts, 4, 5))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es5.ts, 0, 13))
+>_ : Symbol(_, Decl(emitter.pipelineOperatorStage1.es5.ts, 4, 17))
+>map : Symbol(map, Decl(emitter.pipelineOperatorStage1.es5.ts, 0, 35))
+>_ : Symbol(_, Decl(emitter.pipelineOperatorStage1.es5.ts, 4, 17))
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.es5.ts, 4, 28))
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.es5.ts, 4, 28))
+
+const y = ar |> identity;
+>y : Symbol(y, Decl(emitter.pipelineOperatorStage1.es5.ts, 5, 5))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.es5.ts, 0, 13))
+>identity : Symbol(identity, Decl(emitter.pipelineOperatorStage1.es5.ts, 1, 74))
+
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.types b/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.types
new file mode 100644
index 00000000000..963259ec105
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.es5.types
@@ -0,0 +1,48 @@
+=== tests/cases/conformance/emitter/es5/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es5.ts ===
+declare const ar: Iterable<number>;
+>ar : Iterable<number>
+>Iterable : Iterable<T>
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>T : T
+>U : U
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => U
+>v : T
+>T : T
+>U : U
+>Iterable : Iterable<T>
+>U : U
+
+declare function identity<T>(value: T): T;
+>identity : <T>(value: T) => T
+>T : T
+>value : T
+>T : T
+>T : T
+
+const x = ar |> (_ => map(_, x => x + 1));
+>x : Iterable<number>
+>ar |> (_ => map(_, x => x + 1)) : Iterable<number>
+>ar : Iterable<number>
+>(_ => map(_, x => x + 1)) : (_: Iterable<number>) => Iterable<number>
+>_ => map(_, x => x + 1) : (_: Iterable<number>) => Iterable<number>
+>_ : Iterable<number>
+>map(_, x => x + 1) : Iterable<number>
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>_ : Iterable<number>
+>x => x + 1 : (x: number) => number
+>x : number
+>x + 1 : number
+>x : number
+>1 : 1
+
+const y = ar |> identity;
+>y : Iterable<number>
+>ar |> identity : Iterable<number>
+>ar : Iterable<number>
+>identity : <T>(value: T) => T
+
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.js b/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.js
new file mode 100644
index 00000000000..34789659a50
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.js
@@ -0,0 +1,12 @@
+//// [emitter.pipelineOperatorStage1.esnext.ts]
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function identity<T>(value: T): T;
+
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
+
+
+//// [emitter.pipelineOperatorStage1.esnext.js]
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.symbols b/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.symbols
new file mode 100644
index 00000000000..8f63c682905
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.symbols
@@ -0,0 +1,40 @@
+=== tests/cases/conformance/emitter/esnext/pipelineOperatorStage1/emitter.pipelineOperatorStage1.esnext.ts ===
+declare const ar: Iterable<number>;
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.esnext.ts, 0, 13))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : Symbol(map, Decl(emitter.pipelineOperatorStage1.esnext.ts, 0, 35))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 21))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 23))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 21))
+>fn : Symbol(fn, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 43))
+>v : Symbol(v, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 49))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 21))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 23))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>U : Symbol(U, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 23))
+
+declare function identity<T>(value: T): T;
+>identity : Symbol(identity, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 74))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.esnext.ts, 2, 26))
+>value : Symbol(value, Decl(emitter.pipelineOperatorStage1.esnext.ts, 2, 29))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.esnext.ts, 2, 26))
+>T : Symbol(T, Decl(emitter.pipelineOperatorStage1.esnext.ts, 2, 26))
+
+const x = ar |> (_ => map(_, x => x + 1));
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.esnext.ts, 4, 5))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.esnext.ts, 0, 13))
+>_ : Symbol(_, Decl(emitter.pipelineOperatorStage1.esnext.ts, 4, 17))
+>map : Symbol(map, Decl(emitter.pipelineOperatorStage1.esnext.ts, 0, 35))
+>_ : Symbol(_, Decl(emitter.pipelineOperatorStage1.esnext.ts, 4, 17))
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.esnext.ts, 4, 28))
+>x : Symbol(x, Decl(emitter.pipelineOperatorStage1.esnext.ts, 4, 28))
+
+const y = ar |> identity;
+>y : Symbol(y, Decl(emitter.pipelineOperatorStage1.esnext.ts, 5, 5))
+>ar : Symbol(ar, Decl(emitter.pipelineOperatorStage1.esnext.ts, 0, 13))
+>identity : Symbol(identity, Decl(emitter.pipelineOperatorStage1.esnext.ts, 1, 74))
+
diff --git a/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.types b/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.types
new file mode 100644
index 00000000000..da5a8d88ef2
--- /dev/null
+++ b/tests/baselines/reference/emitter.pipelineOperatorStage1.esnext.types
@@ -0,0 +1,48 @@
+=== tests/cases/conformance/emitter/esnext/pipelineOperatorStage1/emitter.pipelineOperatorStage1.esnext.ts ===
+declare const ar: Iterable<number>;
+>ar : Iterable<number>
+>Iterable : Iterable<T>
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>T : T
+>U : U
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => U
+>v : T
+>T : T
+>U : U
+>Iterable : Iterable<T>
+>U : U
+
+declare function identity<T>(value: T): T;
+>identity : <T>(value: T) => T
+>T : T
+>value : T
+>T : T
+>T : T
+
+const x = ar |> (_ => map(_, x => x + 1));
+>x : Iterable<number>
+>ar |> (_ => map(_, x => x + 1)) : Iterable<number>
+>ar : Iterable<number>
+>(_ => map(_, x => x + 1)) : (_: Iterable<number>) => Iterable<number>
+>_ => map(_, x => x + 1) : (_: Iterable<number>) => Iterable<number>
+>_ : Iterable<number>
+>map(_, x => x + 1) : Iterable<number>
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>_ : Iterable<number>
+>x => x + 1 : (x: number) => number
+>x : number
+>x + 1 : number
+>x : number
+>1 : 1
+
+const y = ar |> identity;
+>y : Iterable<number>
+>ar |> identity : Iterable<number>
+>ar : Iterable<number>
+>identity : <T>(value: T) => T
+
diff --git a/tests/baselines/reference/pipelineOperatorStage1.js b/tests/baselines/reference/pipelineOperatorStage1.js
new file mode 100644
index 00000000000..06a75bc2486
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1.js
@@ -0,0 +1,13 @@
+//// [pipelineOperatorStage1.ts]
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+
+const x = ar
+    |> (_ => map(_, x => x + 1))
+    |> (_ => filter(_, x => x > 2));
+
+
+//// [pipelineOperatorStage1.js]
+const x = (_a = ar, _a = (_ => map(_, x => x + 1))(_a), (_ => filter(_, x => x > 2))(_a));
+var _a;
diff --git a/tests/baselines/reference/pipelineOperatorStage1.symbols b/tests/baselines/reference/pipelineOperatorStage1.symbols
new file mode 100644
index 00000000000..1975f320503
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1.symbols
@@ -0,0 +1,49 @@
+=== tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1.ts ===
+declare const ar: Iterable<number>;
+>ar : Symbol(ar, Decl(pipelineOperatorStage1.ts, 0, 13))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : Symbol(map, Decl(pipelineOperatorStage1.ts, 0, 35))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 1, 21))
+>U : Symbol(U, Decl(pipelineOperatorStage1.ts, 1, 23))
+>ar : Symbol(ar, Decl(pipelineOperatorStage1.ts, 1, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 1, 21))
+>fn : Symbol(fn, Decl(pipelineOperatorStage1.ts, 1, 43))
+>v : Symbol(v, Decl(pipelineOperatorStage1.ts, 1, 49))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 1, 21))
+>U : Symbol(U, Decl(pipelineOperatorStage1.ts, 1, 23))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>U : Symbol(U, Decl(pipelineOperatorStage1.ts, 1, 23))
+
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+>filter : Symbol(filter, Decl(pipelineOperatorStage1.ts, 1, 74))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 2, 24))
+>ar : Symbol(ar, Decl(pipelineOperatorStage1.ts, 2, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 2, 24))
+>fn : Symbol(fn, Decl(pipelineOperatorStage1.ts, 2, 43))
+>v : Symbol(v, Decl(pipelineOperatorStage1.ts, 2, 49))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 2, 24))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(pipelineOperatorStage1.ts, 2, 24))
+
+const x = ar
+>x : Symbol(x, Decl(pipelineOperatorStage1.ts, 4, 5))
+>ar : Symbol(ar, Decl(pipelineOperatorStage1.ts, 0, 13))
+
+    |> (_ => map(_, x => x + 1))
+>_ : Symbol(_, Decl(pipelineOperatorStage1.ts, 5, 8))
+>map : Symbol(map, Decl(pipelineOperatorStage1.ts, 0, 35))
+>_ : Symbol(_, Decl(pipelineOperatorStage1.ts, 5, 8))
+>x : Symbol(x, Decl(pipelineOperatorStage1.ts, 5, 19))
+>x : Symbol(x, Decl(pipelineOperatorStage1.ts, 5, 19))
+
+    |> (_ => filter(_, x => x > 2));
+>_ : Symbol(_, Decl(pipelineOperatorStage1.ts, 6, 8))
+>filter : Symbol(filter, Decl(pipelineOperatorStage1.ts, 1, 74))
+>_ : Symbol(_, Decl(pipelineOperatorStage1.ts, 6, 8))
+>x : Symbol(x, Decl(pipelineOperatorStage1.ts, 6, 22))
+>x : Symbol(x, Decl(pipelineOperatorStage1.ts, 6, 22))
+
diff --git a/tests/baselines/reference/pipelineOperatorStage1.types b/tests/baselines/reference/pipelineOperatorStage1.types
new file mode 100644
index 00000000000..1eb6ad05c39
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1.types
@@ -0,0 +1,63 @@
+=== tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1.ts ===
+declare const ar: Iterable<number>;
+>ar : Iterable<number>
+>Iterable : Iterable<T>
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>T : T
+>U : U
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => U
+>v : T
+>T : T
+>U : U
+>Iterable : Iterable<T>
+>U : U
+
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+>filter : <T>(ar: Iterable<T>, fn: (v: T) => boolean) => Iterable<T>
+>T : T
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => boolean
+>v : T
+>T : T
+>Iterable : Iterable<T>
+>T : T
+
+const x = ar
+>x : Iterable<number>
+>ar    |> (_ => map(_, x => x + 1))    |> (_ => filter(_, x => x > 2)) : Iterable<number>
+>ar    |> (_ => map(_, x => x + 1)) : Iterable<number>
+>ar : Iterable<number>
+
+    |> (_ => map(_, x => x + 1))
+>(_ => map(_, x => x + 1)) : (_: Iterable<number>) => Iterable<number>
+>_ => map(_, x => x + 1) : (_: Iterable<number>) => Iterable<number>
+>_ : Iterable<number>
+>map(_, x => x + 1) : Iterable<number>
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>_ : Iterable<number>
+>x => x + 1 : (x: number) => number
+>x : number
+>x + 1 : number
+>x : number
+>1 : 1
+
+    |> (_ => filter(_, x => x > 2));
+>(_ => filter(_, x => x > 2)) : (_: Iterable<number>) => Iterable<number>
+>_ => filter(_, x => x > 2) : (_: Iterable<number>) => Iterable<number>
+>_ : Iterable<number>
+>filter(_, x => x > 2) : Iterable<number>
+>filter : <T>(ar: Iterable<T>, fn: (v: T) => boolean) => Iterable<T>
+>_ : Iterable<number>
+>x => x > 2 : (x: number) => boolean
+>x : number
+>x > 2 : boolean
+>x : number
+>2 : 2
+
diff --git a/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.errors.txt b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.errors.txt
new file mode 100644
index 00000000000..07be1e84722
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.errors.txt
@@ -0,0 +1,14 @@
+tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts(5,11): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'Number' has no compatible call signatures.
+
+
+==== tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts (1 errors) ====
+    declare const ar: Iterable<number>;
+    declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+    declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+    
+    const x = ar
+              ~~
+        |> 1;
+    ~~~~~~~~
+!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'Number' has no compatible call signatures.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.js b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.js
new file mode 100644
index 00000000000..68cf74fc7bc
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.js
@@ -0,0 +1,12 @@
+//// [pipelineOperatorStage1WithNonFunctionRHS.ts]
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+
+const x = ar
+    |> 1;
+
+
+//// [pipelineOperatorStage1WithNonFunctionRHS.js]
+const x = (_a = ar, 1(_a));
+var _a;
diff --git a/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.symbols b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.symbols
new file mode 100644
index 00000000000..5b8ce844959
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.symbols
@@ -0,0 +1,37 @@
+=== tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts ===
+declare const ar: Iterable<number>;
+>ar : Symbol(ar, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 0, 13))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : Symbol(map, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 0, 35))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 21))
+>U : Symbol(U, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 23))
+>ar : Symbol(ar, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 21))
+>fn : Symbol(fn, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 43))
+>v : Symbol(v, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 49))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 21))
+>U : Symbol(U, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 23))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>U : Symbol(U, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 23))
+
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+>filter : Symbol(filter, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 1, 74))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 24))
+>ar : Symbol(ar, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 27))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 24))
+>fn : Symbol(fn, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 43))
+>v : Symbol(v, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 49))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 24))
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>T : Symbol(T, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 2, 24))
+
+const x = ar
+>x : Symbol(x, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 4, 5))
+>ar : Symbol(ar, Decl(pipelineOperatorStage1WithNonFunctionRHS.ts, 0, 13))
+
+    |> 1;
+
diff --git a/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.types b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.types
new file mode 100644
index 00000000000..febaed94923
--- /dev/null
+++ b/tests/baselines/reference/pipelineOperatorStage1WithNonFunctionRHS.types
@@ -0,0 +1,39 @@
+=== tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts ===
+declare const ar: Iterable<number>;
+>ar : Iterable<number>
+>Iterable : Iterable<T>
+
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+>map : <T, U>(ar: Iterable<T>, fn: (v: T) => U) => Iterable<U>
+>T : T
+>U : U
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => U
+>v : T
+>T : T
+>U : U
+>Iterable : Iterable<T>
+>U : U
+
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+>filter : <T>(ar: Iterable<T>, fn: (v: T) => boolean) => Iterable<T>
+>T : T
+>ar : Iterable<T>
+>Iterable : Iterable<T>
+>T : T
+>fn : (v: T) => boolean
+>v : T
+>T : T
+>Iterable : Iterable<T>
+>T : T
+
+const x = ar
+>x : any
+>ar    |> 1 : any
+>ar : Iterable<number>
+
+    |> 1;
+>1 : 1
+
diff --git a/tests/cases/conformance/emitter/es2015/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es2015.ts b/tests/cases/conformance/emitter/es2015/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es2015.ts
new file mode 100644
index 00000000000..4e0a7eaeead
--- /dev/null
+++ b/tests/cases/conformance/emitter/es2015/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es2015.ts
@@ -0,0 +1,8 @@
+// @experimentalPipelineStage1: true
+// @target: es2015
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function identity<T>(value: T): T;
+
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
diff --git a/tests/cases/conformance/emitter/es5/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es5.ts b/tests/cases/conformance/emitter/es5/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es5.ts
new file mode 100644
index 00000000000..aec2b3a7175
--- /dev/null
+++ b/tests/cases/conformance/emitter/es5/pipelineOperatorStage1/emitter.pipelineOperatorStage1.es5.ts
@@ -0,0 +1,9 @@
+// @experimentalPipelineStage1: true
+// @target: es5
+// @lib: es2015
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function identity<T>(value: T): T;
+
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
diff --git a/tests/cases/conformance/emitter/esnext/pipelineOperatorStage1/emitter.pipelineOperatorStage1.esnext.ts b/tests/cases/conformance/emitter/esnext/pipelineOperatorStage1/emitter.pipelineOperatorStage1.esnext.ts
new file mode 100644
index 00000000000..6388ed9a539
--- /dev/null
+++ b/tests/cases/conformance/emitter/esnext/pipelineOperatorStage1/emitter.pipelineOperatorStage1.esnext.ts
@@ -0,0 +1,8 @@
+// @experimentalPipelineStage1: true
+// @target: esnext
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function identity<T>(value: T): T;
+
+const x = ar |> (_ => map(_, x => x + 1));
+const y = ar |> identity;
diff --git a/tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1.ts b/tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1.ts
new file mode 100644
index 00000000000..8d2f53eeca3
--- /dev/null
+++ b/tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1.ts
@@ -0,0 +1,9 @@
+// @experimentalPipelineStage1: true
+// @target: es2015
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+
+const x = ar
+    |> (_ => map(_, x => x + 1))
+    |> (_ => filter(_, x => x > 2));
diff --git a/tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts b/tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts
new file mode 100644
index 00000000000..15b7dff23d6
--- /dev/null
+++ b/tests/cases/conformance/expressions/pipelineOperatorStage1/pipelineOperatorStage1WithNonFunctionRHS.ts
@@ -0,0 +1,8 @@
+// @experimentalPipelineStage1: true
+// @target: es2015
+declare const ar: Iterable<number>;
+declare function map<T, U>(ar: Iterable<T>, fn: (v: T) => U): Iterable<U>;
+declare function filter<T>(ar: Iterable<T>, fn: (v: T) => boolean): Iterable<T>;
+
+const x = ar
+    |> 1;