Fix up calls and pipelines

crates/nu-command/src/benchmark.rs

@@ -34,7 +34,7 @@ impl Command for Benchmark {
 
         let state = context.enter_scope();
         let start_time = Instant::now();
-        eval_block(&state, block)?;
+        eval_block(&state, block, Value::nothing())?;
         let end_time = Instant::now();
         println!("{} ms", (end_time - start_time).as_millis());
         Ok(Value::Nothing {

crates/nu-command/src/default_context.rs

@@ -5,7 +5,7 @@ use nu_protocol::{
     Signature, SyntaxShape,
 };
 
-use crate::{Alias, Benchmark, BuildString, Def, For, If, Let, LetEnv};
+use crate::{Alias, Benchmark, BuildString, Def, For, If, Length, Let, LetEnv};
 
 pub fn create_default_context() -> Rc<RefCell<EngineState>> {
     let engine_state = Rc::new(RefCell::new(EngineState::new()));
@@ -33,6 +33,8 @@ pub fn create_default_context() -> Rc<RefCell<EngineState>> {
 
         working_set.add_decl(Box::new(Benchmark));
 
+        working_set.add_decl(Box::new(Length));
+
         let sig = Signature::build("exit");
         working_set.add_decl(sig.predeclare());
         let sig = Signature::build("vars");

crates/nu-command/src/for_.rs

@@ -33,7 +33,7 @@ impl Command for For {
         &self,
         context: &EvaluationContext,
         call: &Call,
-        _input: Value,
+        input: Value,
     ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
         let var_id = call.positional[0]
             .as_var()
@@ -62,7 +62,7 @@ impl Command for For {
                 break;
             } else {
                 state.add_var(var_id, x.clone());
-                eval_block(&state, block)?;
+                eval_block(&state, block, input.clone())?;
             }
             if let Value::Int { ref mut val, .. } = x {
                 *val += 1

crates/nu-command/src/if_.rs

@@ -29,7 +29,7 @@ impl Command for If {
         &self,
         context: &EvaluationContext,
         call: &Call,
-        _input: Value,
+        input: Value,
     ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
         let cond = &call.positional[0];
         let then_block = call.positional[1]
@@ -44,13 +44,13 @@ impl Command for If {
                 if val {
                     let block = engine_state.get_block(then_block);
                     let state = context.enter_scope();
-                    eval_block(&state, block)
+                    eval_block(&state, block, input)
                 } else if let Some(else_case) = else_case {
                     if let Some(else_expr) = else_case.as_keyword() {
                         if let Some(block_id) = else_expr.as_block() {
                             let block = engine_state.get_block(block_id);
                             let state = context.enter_scope();
-                            eval_block(&state, block)
+                            eval_block(&state, block, input)
                         } else {
                             eval_expression(context, else_expr)
                         }

crates/nu-command/src/length.rs

@@ -0,0 +1,49 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EvaluationContext};
+use nu_protocol::{Signature, Value};
+
+pub struct Length;
+
+impl Command for Length {
+    fn name(&self) -> &str {
+        "length"
+    }
+
+    fn usage(&self) -> &str {
+        "Count the number of elements in the input."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("length")
+    }
+
+    fn run(
+        &self,
+        _context: &EvaluationContext,
+        call: &Call,
+        input: Value,
+    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
+        match input {
+            Value::List { val, .. } => {
+                let length = val.count();
+
+                Ok(Value::Int {
+                    val: length as i64,
+                    span: call.head,
+                })
+            }
+            Value::Table { val, .. } => {
+                let length = val.count();
+
+                Ok(Value::Int {
+                    val: length as i64,
+                    span: call.head,
+                })
+            }
+            _ => Ok(Value::Int {
+                val: 1,
+                span: call.head,
+            }),
+        }
+    }
+}

crates/nu-command/src/lib.rs

@@ -5,6 +5,7 @@ mod def;
 mod default_context;
 mod for_;
 mod if_;
+mod length;
 mod let_;
 mod let_env;
 
@@ -15,5 +16,6 @@ pub use def::Def;
 pub use default_context::create_default_context;
 pub use for_::For;
 pub use if_::If;
+pub use length::Length;
 pub use let_::Let;
 pub use let_env::LetEnv;