From 4ce9a5c8940502f5af88dd79e4aa4c85c179c3c2 Mon Sep 17 00:00:00 2001
From: JT <jonathan.d.turner@gmail.com>
Date: Tue, 7 Sep 2021 06:05:46 +1200
Subject: [PATCH] Make variable assignment convert streams to full values

---
 TODO.md                                       |  3 +++
 .../src/engine/evaluation_context.rs          | 23 +++++++++++++++++++
 src/tests.rs                                  |  8 +++++++
 3 files changed, 34 insertions(+)

diff --git a/TODO.md b/TODO.md
index 38f329433a..9c819da580 100644
--- a/TODO.md
+++ b/TODO.md
@@ -14,12 +14,15 @@
 - [x] parsing tables
 - [x] Block params
 - [x] Ranges
+- [ ] Iteration (`each`) over tables
+- [ ] ctrl-c support
 - [ ] Column path
 - [ ] ...rest without calling it rest
 - [ ] operator overflow
 - [ ] finish operator type-checking
 - [ ] Source
 - [ ] Autoenv
+- [ ] Externals
 - [ ] let [first, rest] = [1, 2, 3]
   
 ## Maybe: 
diff --git a/crates/nu-protocol/src/engine/evaluation_context.rs b/crates/nu-protocol/src/engine/evaluation_context.rs
index 5229659343..8eaa68752e 100644
--- a/crates/nu-protocol/src/engine/evaluation_context.rs
+++ b/crates/nu-protocol/src/engine/evaluation_context.rs
@@ -22,6 +22,29 @@ impl EvaluationContext {
     }
 
     pub fn add_var(&self, var_id: VarId, value: Value) {
+        // We need to make values concreate before we assign them to variables, as stream values
+        // will drain and remain drained.
+        //
+        // TODO: find a good home for this
+        // TODO: add ctrl-c support
+
+        let value = match value {
+            Value::RowStream {
+                headers,
+                stream,
+                span,
+            } => Value::Table {
+                headers,
+                val: stream.collect(),
+                span,
+            },
+            Value::ValueStream { stream, span } => Value::List {
+                val: stream.collect(),
+                span,
+            },
+            x => x,
+        };
+
         self.stack.add_var(var_id, value);
     }
 
diff --git a/src/tests.rs b/src/tests.rs
index c7ed9041b2..a3b90da787 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -228,3 +228,11 @@ fn range_iteration2() -> TestResult {
 fn simple_value_iteration() -> TestResult {
     run_test("4 | each { $it + 10 }", "14")
 }
+
+#[test]
+fn concrete_variable_assignment() -> TestResult {
+    run_test(
+        "let x = (1..100 | each { |y| $y + 100 }); $x | length; $x | length",
+        "100",
+    )
+}