Improve external output in subexprs (#294)

crates/nu-cli/src/completions.rs

@@ -72,8 +72,12 @@ impl Completer for NuCompleter {
                             parse(&mut working_set, None, custom_completion.as_bytes(), false);
 
                         let mut stack = Stack::default();
-                        let result =
-                            eval_block(&self.engine_state, &mut stack, &block, PipelineData::new());
+                        let result = eval_block(
+                            &self.engine_state,
+                            &mut stack,
+                            &block,
+                            PipelineData::new(flat.0),
+                        );
 
                         let v: Vec<_> = match result {
                             Ok(pd) => pd

crates/nu-command/src/conversions/into/filesize.rs

@@ -131,7 +131,7 @@ pub fn action(input: &Value, span: Span) -> Value {
 fn int_from_string(a_string: &str, span: Span) -> Result<i64, ShellError> {
     match a_string.parse::<bytesize::ByteSize>() {
         Ok(n) => Ok(n.0 as i64),
-        Err(_) => Err(ShellError::CantConvert("int".into(), span)),
+        Err(_) => Err(ShellError::CantConvert("int".into(), "string".into(), span)),
     }
 }
 

crates/nu-command/src/conversions/into/int.rs

@@ -137,7 +137,11 @@ fn int_from_string(a_string: &str, span: Span) -> Result<i64, ShellError> {
         Ok(n) => Ok(n),
         Err(_) => match a_string.parse::<f64>() {
             Ok(f) => Ok(f as i64),
-            _ => Err(ShellError::CantConvert("into int".into(), span)),
+            _ => Err(ShellError::CantConvert(
+                "into int".into(),
+                "string".into(),
+                span,
+            )),
         },
     }
 }

crates/nu-command/src/conversions/into/string.rs

@@ -229,11 +229,8 @@ pub fn action(
                 span,
             ),
         },
-        _ => Value::Error {
-            error: ShellError::CantConvert(
-                String::from(" into string. Probably this type is not supported yet"),
-                span,
-            ),
+        x => Value::Error {
+            error: ShellError::CantConvert(String::from("string"), x.get_type().to_string(), span),
         },
     }
 }

crates/nu-command/src/core_commands/alias.rs

@@ -28,9 +28,9 @@ impl Command for Alias {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/def.rs

@@ -29,9 +29,9 @@ impl Command for Def {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/echo.rs

@@ -1,9 +1,7 @@
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value, ValueStream,
-};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, SyntaxShape, Value, ValueStream};
 
 #[derive(Clone)]
 pub struct Echo;
@@ -43,7 +41,7 @@ impl Command for Echo {
                 //  When there are no elements, we echo the empty string
                 std::cmp::Ordering::Less => PipelineData::Value(Value::String {
                     val: "".to_string(),
-                    span: Span::unknown(),
+                    span: call.head,
                 }),
             }
         })

crates/nu-command/src/core_commands/export_def.rs

@@ -29,9 +29,9 @@ impl Command for ExportDef {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/for_.rs

@@ -44,6 +44,7 @@ impl Command for For {
         call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let head = call.head;
         let var_id = call.positional[0]
             .as_var()
             .expect("internal error: missing variable");
@@ -69,8 +70,8 @@ impl Command for For {
                     stack.add_var(var_id, x);
 
                     //let block = engine_state.get_block(block_id);
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new()) {
-                        Ok(pipeline_data) => pipeline_data.into_value(),
+                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(head)) {
+                        Ok(pipeline_data) => pipeline_data.into_value(head),
                         Err(error) => Value::Error { error },
                     }
                 })
@@ -81,8 +82,8 @@ impl Command for For {
                     stack.add_var(var_id, x);
 
                     //let block = engine_state.get_block(block_id);
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new()) {
-                        Ok(pipeline_data) => pipeline_data.into_value(),
+                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(head)) {
+                        Ok(pipeline_data) => pipeline_data.into_value(head),
                         Err(error) => Value::Error { error },
                     }
                 })
@@ -90,7 +91,7 @@ impl Command for For {
             x => {
                 stack.add_var(var_id, x);
 
-                eval_block(&engine_state, &mut stack, &block, PipelineData::new())
+                eval_block(&engine_state, &mut stack, &block, PipelineData::new(head))
             }
         }
     }

crates/nu-command/src/core_commands/hide.rs

@@ -22,9 +22,9 @@ impl Command for Hide {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/if_.rs

@@ -40,9 +40,9 @@ impl Command for If {
         let else_case = call.positional.get(2);
 
         let result = eval_expression(engine_state, stack, cond)?;
-        match result {
+        match &result {
             Value::Bool { val, .. } => {
-                if val {
+                if *val {
                     let block = engine_state.get_block(then_block);
                     let mut stack = stack.collect_captures(&block.captures);
                     eval_block(engine_state, &mut stack, block, input)
@@ -61,10 +61,14 @@ impl Command for If {
                             .map(|x| x.into_pipeline_data())
                     }
                 } else {
-                    Ok(PipelineData::new())
+                    Ok(PipelineData::new(call.head))
                 }
             }
-            _ => Err(ShellError::CantConvert("bool".into(), result.span()?)),
+            x => Err(ShellError::CantConvert(
+                "bool".into(),
+                x.get_type().to_string(),
+                result.span()?,
+            )),
         }
     }
 }

crates/nu-command/src/core_commands/let_.rs

@@ -45,6 +45,6 @@ impl Command for Let {
         //println!("Adding: {:?} to {}", rhs, var_id);
 
         stack.add_var(var_id, rhs);
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/module.rs

@@ -28,9 +28,9 @@ impl Command for Module {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/register.rs

@@ -26,9 +26,9 @@ impl Command for Register {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/core_commands/use_.rs

@@ -22,9 +22,9 @@ impl Command for Use {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/date/to_timezone.rs

@@ -111,7 +111,7 @@ fn _to_timezone(dt: DateTime<FixedOffset>, timezone: &Spanned<String>, span: Spa
     match datetime_in_timezone(&dt, timezone.item.as_str()) {
         Ok(dt) => Value::Date { val: dt, span },
         Err(_) => Value::Error {
-            error: ShellError::UnsupportedInput(String::from("invalid time zone"), Span::unknown()),
+            error: ShellError::UnsupportedInput(String::from("invalid time zone"), span),
         },
     }
 }

crates/nu-command/src/env/let_env.rs

@@ -46,6 +46,6 @@ impl Command for LetEnv {
         //println!("Adding: {:?} to {}", rhs, var_id);
 
         stack.add_env_var(env_var, rhs);
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/env/with_env.rs

@@ -91,7 +91,11 @@ impl TryFrom<&Value> for EnvVar {
                 Ok(EnvVar::Proper(s))
             }
         } else {
-            Err(ShellError::CantConvert("string".into(), value.span()?))
+            Err(ShellError::CantConvert(
+                "string".into(),
+                value.get_type().to_string(),
+                value.span()?,
+            ))
         }
     }
 }
@@ -123,9 +127,10 @@ fn with_env(
                             env.insert(k.to_string(), v.try_into()?);
                         }
                     }
-                    _ => {
+                    x => {
                         return Err(ShellError::CantConvert(
                             "string list or single row".into(),
+                            x.get_type().to_string(),
                             call.positional[1].span,
                         ));
                     }
@@ -145,9 +150,10 @@ fn with_env(
                 env.insert(k.clone(), v.try_into()?);
             }
         }
-        _ => {
+        x => {
             return Err(ShellError::CantConvert(
                 "string list or single row".into(),
+                x.get_type().to_string(),
                 call.positional[1].span,
             ));
         }

crates/nu-command/src/example_test.rs

@@ -2,7 +2,7 @@ use nu_engine::eval_block;
 use nu_parser::parse;
 use nu_protocol::{
     engine::{Command, EngineState, Stack, StateWorkingSet},
-    PipelineData,
+    PipelineData, Span,
 };
 
 use crate::To;
@@ -56,10 +56,15 @@ pub fn test_examples(cmd: impl Command + 'static) {
 
         let mut stack = Stack::new();
 
-        match eval_block(&engine_state, &mut stack, &block, PipelineData::new()) {
+        match eval_block(
+            &engine_state,
+            &mut stack,
+            &block,
+            PipelineData::new(Span::unknown()),
+        ) {
             Err(err) => panic!("test eval error in `{}`: {:?}", example.example, err),
             Ok(result) => {
-                let result = result.into_value();
+                let result = result.into_value(Span::unknown());
                 println!("input: {}", example.example);
                 println!("result: {:?}", result);
                 println!("done: {:?}", start.elapsed());

crates/nu-command/src/experimental/git.rs

@@ -44,13 +44,13 @@ impl Command for Git {
                     }
                     Err(_err) => {
                         // FIXME: Move this to an external signature and add better error handling
-                        Ok(PipelineData::new())
+                        Ok(PipelineData::new(call.head))
                     }
                 }
             }
             Err(_err) => {
                 // FIXME: Move this to an external signature and add better error handling
-                Ok(PipelineData::new())
+                Ok(PipelineData::new(call.head))
             }
         }
     }

crates/nu-command/src/experimental/git_checkout.rs

@@ -59,13 +59,13 @@ impl Command for GitCheckout {
                     }
                     Err(_err) => {
                         // FIXME: Move this to an external signature and add better error handling
-                        Ok(PipelineData::new())
+                        Ok(PipelineData::new(call.head))
                     }
                 }
             }
             Err(_err) => {
                 // FIXME: Move this to an external signature and add better error handling
-                Ok(PipelineData::new())
+                Ok(PipelineData::new(call.head))
             }
         }
     }

crates/nu-command/src/experimental/list_git_branches.rs

@@ -66,10 +66,10 @@ impl Command for ListGitBranches {
                     .into_iter()
                     .into_pipeline_data(engine_state.ctrlc.clone()))
             } else {
-                Ok(PipelineData::new())
+                Ok(PipelineData::new(call.head))
             }
         } else {
-            Ok(PipelineData::new())
+            Ok(PipelineData::new(call.head))
         }
     }
 }

crates/nu-command/src/filesystem/cd.rs

@@ -43,6 +43,6 @@ impl Command for Cd {
         //FIXME: this only changes the current scope, but instead this environment variable
         //should probably be a block that loads the information from the state in the overlay
         stack.add_env_var("PWD".into(), path);
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/filesystem/cp.rs

@@ -204,6 +204,6 @@ impl Command for Cp {
             }
         }
 
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/filesystem/mv.rs

@@ -130,7 +130,7 @@ impl Command for Mv {
             move_file(call, &entry, &destination)?
         }
 
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }
 

crates/nu-command/src/filesystem/touch.rs

@@ -49,6 +49,6 @@ impl Command for Touch {
             }
         }
 
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/filters/each.rs

@@ -102,8 +102,8 @@ impl Command for Each {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new()) {
-                        Ok(v) => v.into_value(),
+                    match eval_block(&engine_state, &mut stack, &block, PipelineData::new(span)) {
+                        Ok(v) => v.into_value(span),
                         Err(error) => Value::Error { error },
                     }
                 })
@@ -136,7 +136,7 @@ impl Command for Each {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new())? {
+                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span))? {
                         PipelineData::Value(Value::Record {
                             mut cols, mut vals, ..
                         }) => {
@@ -146,7 +146,7 @@ impl Command for Each {
                         }
                         x => {
                             output_cols.push(col);
-                            output_vals.push(x.into_value());
+                            output_vals.push(x.into_value(span));
                         }
                     }
                 }
@@ -167,7 +167,7 @@ impl Command for Each {
                     }
                 }
 
-                eval_block(&engine_state, &mut stack, block, PipelineData::new())
+                eval_block(&engine_state, &mut stack, block, PipelineData::new(span))
             }
         }
     }

crates/nu-command/src/filters/par_each.rs

@@ -88,7 +88,7 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new()) {
+                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -129,7 +129,7 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new()) {
+                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -169,7 +169,7 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new()) {
+                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span)) {
                         Ok(v) => v,
                         Err(error) => Value::Error { error }.into_pipeline_data(),
                     }
@@ -206,7 +206,7 @@ impl Command for ParEach {
                         }
                     }
 
-                    match eval_block(&engine_state, &mut stack, block, PipelineData::new())? {
+                    match eval_block(&engine_state, &mut stack, block, PipelineData::new(span))? {
                         PipelineData::Value(Value::Record {
                             mut cols, mut vals, ..
                         }) => {
@@ -216,7 +216,7 @@ impl Command for ParEach {
                         }
                         x => {
                             output_cols.push(col);
-                            output_vals.push(x.into_value());
+                            output_vals.push(x.into_value(span));
                         }
                     }
                 }
@@ -237,7 +237,7 @@ impl Command for ParEach {
                     }
                 }
 
-                eval_block(&engine_state, &mut stack, block, PipelineData::new())
+                eval_block(&engine_state, &mut stack, block, PipelineData::new(span))
             }
         }
     }

crates/nu-command/src/filters/where_.rs

@@ -29,6 +29,7 @@ impl Command for Where {
         call: &Call,
         input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let head = call.head;
         let cond = call.positional[0].clone();
 
         let ctrlc = engine_state.ctrlc.clone();
@@ -79,7 +80,7 @@ impl Command for Where {
                 if result.is_true() {
                     Ok(x.into_pipeline_data())
                 } else {
-                    Ok(PipelineData::new())
+                    Ok(PipelineData::new(head))
                 }
             }
         }

crates/nu-command/src/formats/from/command.rs

@@ -22,9 +22,9 @@ impl Command for From {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/formats/from/json.rs

@@ -128,7 +128,11 @@ fn convert_nujson_to_value(value: &nu_json::Value, span: Span) -> Value {
         nu_json::Value::U64(u) => {
             if *u > i64::MAX as u64 {
                 Value::Error {
-                    error: ShellError::CantConvert("i64 sized integer".into(), span),
+                    error: ShellError::CantConvert(
+                        "i64 sized integer".into(),
+                        "larger than i64".into(),
+                        span,
+                    ),
                 }
             } else {
                 Value::Int {
@@ -151,6 +155,7 @@ fn convert_string_to_value(string_input: String, span: Span) -> Result<Value, Sh
 
         Err(_x) => Err(ShellError::CantConvert(
             "structured data from json".into(),
+            "string".into(),
             span,
         )),
     }

crates/nu-command/src/formats/to/command.rs

@@ -22,9 +22,9 @@ impl Command for To {
         &self,
         _engine_state: &EngineState,
         _stack: &mut Stack,
-        _call: &Call,
+        call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, ShellError> {
-        Ok(PipelineData::new())
+        Ok(PipelineData::new(call.head))
     }
 }

crates/nu-command/src/formats/to/json.rs

@@ -127,7 +127,11 @@ fn to_json(
                 }
                 .into_pipeline_data()),
                 _ => Ok(Value::Error {
-                    error: ShellError::CantConvert("JSON".into(), name_span),
+                    error: ShellError::CantConvert(
+                        "JSON".into(),
+                        value.get_type().to_string(),
+                        name_span,
+                    ),
                 }
                 .into_pipeline_data()),
             }
@@ -141,12 +145,20 @@ fn to_json(
                             span: name_span,
                         },
                         _ => Value::Error {
-                            error: ShellError::CantConvert("JSON".into(), name_span),
+                            error: ShellError::CantConvert(
+                                "JSON".into(),
+                                value.get_type().to_string(),
+                                name_span,
+                            ),
                         },
                     }
                 } else {
                     Value::Error {
-                        error: ShellError::CantConvert("JSON".into(), name_span),
+                        error: ShellError::CantConvert(
+                            "JSON".into(),
+                            value.get_type().to_string(),
+                            name_span,
+                        ),
                     }
                 }
             })

crates/nu-command/src/math/max.rs

@@ -41,7 +41,7 @@ impl Command for SubCommand {
 
 pub fn maximum(values: &[Value], head: &Span) -> Result<Value, ShellError> {
     let max_func = reducer_for(Reduce::Maximum);
-    max_func(Value::nothing(), values.to_vec(), *head)
+    max_func(Value::nothing(*head), values.to_vec(), *head)
 }
 
 #[cfg(test)]

crates/nu-command/src/math/min.rs

@@ -41,7 +41,7 @@ impl Command for SubCommand {
 
 pub fn minimum(values: &[Value], head: &Span) -> Result<Value, ShellError> {
     let min_func = reducer_for(Reduce::Minimum);
-    min_func(Value::nothing(), values.to_vec(), *head)
+    min_func(Value::nothing(*head), values.to_vec(), *head)
 }
 
 #[cfg(test)]

crates/nu-command/src/math/product.rs

@@ -42,7 +42,7 @@ impl Command for SubCommand {
 /// Calculate product of given values
 pub fn product(values: &[Value], head: &Span) -> Result<Value, ShellError> {
     let product_func = reducer_for(Reduce::Product);
-    product_func(Value::nothing(), values.to_vec(), *head)
+    product_func(Value::nothing(*head), values.to_vec(), *head)
 }
 
 #[cfg(test)]

crates/nu-command/src/math/reducers.rs

@@ -24,7 +24,7 @@ pub fn reducer_for(command: Reduce) -> ReducerFunction {
 pub fn max(data: Vec<Value>, head: Span) -> Result<Value, ShellError> {
     let mut biggest = data
         .first()
-        .ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), Span::unknown()))?
+        .ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), head))?
         .clone();
 
     for value in &data {
@@ -48,7 +48,7 @@ pub fn max(data: Vec<Value>, head: Span) -> Result<Value, ShellError> {
 pub fn min(data: Vec<Value>, head: Span) -> Result<Value, ShellError> {
     let mut smallest = data
         .first()
-        .ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), Span::unknown()))?
+        .ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), head))?
         .clone();
 
     for value in &data {
@@ -87,9 +87,9 @@ pub fn sum(data: Vec<Value>, head: Span) -> Result<Value, ShellError> {
         }),
         None => Err(ShellError::UnsupportedInput(
             "Empty input".to_string(),
-            Span::unknown(),
+            head,
         )),
-        _ => Ok(Value::nothing()),
+        _ => Ok(Value::nothing(head)),
     }?;
 
     for value in &data {
@@ -127,7 +127,7 @@ pub fn product(data: Vec<Value>, head: Span) -> Result<Value, ShellError> {
             "Empty input".to_string(),
             Span::unknown(),
         )),
-        _ => Ok(Value::nothing()),
+        _ => Ok(Value::nothing(head)),
     }?;
 
     for value in &data {

crates/nu-command/src/math/sum.rs

@@ -48,7 +48,7 @@ impl Command for SubCommand {
 
 pub fn summation(values: &[Value], head: &Span) -> Result<Value, ShellError> {
     let sum_func = reducer_for(Reduce::Summation);
-    sum_func(Value::nothing(), values.to_vec(), *head)
+    sum_func(Value::nothing(*head), values.to_vec(), *head)
 }
 
 #[cfg(test)]

crates/nu-command/src/strings/format/command.rs

@@ -38,7 +38,7 @@ impl Command for Format {
             Ok(pattern) => {
                 let string_pattern = pattern.as_string().unwrap();
                 let ops = extract_formatting_operations(string_pattern);
-                format(input, &ops)
+                format(input, &ops, call.head)
             }
         }
     }
@@ -116,8 +116,9 @@ fn extract_formatting_operations(input: String) -> Vec<FormatOperation> {
 fn format(
     input_data: PipelineData,
     format_operations: &[FormatOperation],
+    span: Span,
 ) -> Result<PipelineData, ShellError> {
-    let data_as_value = input_data.into_value();
+    let data_as_value = input_data.into_value(span);
 
     //  We can only handle a Record or a List of Record's
     match data_as_value {

crates/nu-command/src/system/benchmark.rs

@@ -39,7 +39,13 @@ impl Command for Benchmark {
 
         let mut stack = stack.collect_captures(&block.captures);
         let start_time = Instant::now();
-        eval_block(engine_state, &mut stack, block, PipelineData::new())?.into_value();
+        eval_block(
+            engine_state,
+            &mut stack,
+            block,
+            PipelineData::new(call.head),
+        )?
+        .into_value(call.head);
 
         let end_time = Instant::now();
 

crates/nu-command/src/system/run_external.rs

@@ -161,9 +161,9 @@ impl ExternalCommand {
                     });
 
                     // The ValueStream is consumed by the next expression in the pipeline
-                    ChannelReceiver::new(rx).into_pipeline_data(ctrlc)
+                    ChannelReceiver::new(rx, self.name.span).into_pipeline_data(ctrlc)
                 } else {
-                    PipelineData::new()
+                    PipelineData::new(self.name.span)
                 };
 
                 match child.wait() {
@@ -214,11 +214,12 @@ enum Data {
 // It implements iterator so it can be used as a ValueStream
 struct ChannelReceiver {
     rx: mpsc::Receiver<Data>,
+    span: Span,
 }
 
 impl ChannelReceiver {
-    pub fn new(rx: mpsc::Receiver<Data>) -> Self {
-        Self { rx }
+    pub fn new(rx: mpsc::Receiver<Data>, span: Span) -> Self {
+        Self { rx, span }
     }
 }
 
@@ -230,11 +231,11 @@ impl Iterator for ChannelReceiver {
             Ok(v) => match v {
                 Data::String(s) => Some(Value::String {
                     val: s,
-                    span: Span::unknown(),
+                    span: self.span,
                 }),
                 Data::Bytes(b) => Some(Value::Binary {
                     val: b,
-                    span: Span::unknown(),
+                    span: self.span,
                 }),
             },
             Err(_) => None,

crates/nu-command/src/viewers/griddle.rs

@@ -70,7 +70,7 @@ prints out the list properly."#
                         separator_param,
                     ))
                 } else {
-                    Ok(PipelineData::new())
+                    Ok(PipelineData::new(call.head))
                 }
             }
             PipelineData::Stream(stream) => {
@@ -86,7 +86,7 @@ prints out the list properly."#
                     ))
                 } else {
                     // dbg!(data);
-                    Ok(PipelineData::new())
+                    Ok(PipelineData::new(call.head))
                 }
             }
             PipelineData::Value(Value::Record { cols, vals, .. }) => {

crates/nu-command/src/viewers/table.rs

@@ -48,7 +48,7 @@ impl Command for Table {
                     }
                     .into_pipeline_data())
                 } else {
-                    Ok(PipelineData::new())
+                    Ok(PipelineData::new(call.head))
                 }
             }
             PipelineData::Stream(stream) => {
@@ -63,7 +63,7 @@ impl Command for Table {
                     }
                     .into_pipeline_data())
                 } else {
-                    Ok(PipelineData::new())
+                    Ok(PipelineData::new(call.head))
                 }
             }
             PipelineData::Value(Value::Record { cols, vals, .. }) => {

crates/nu-engine/src/eval.rs

@@ -178,7 +178,11 @@ pub fn eval_expression(
         }),
         Expr::ValueWithUnit(e, unit) => match eval_expression(engine_state, stack, e)? {
             Value::Int { val, .. } => Ok(compute(val, unit.item, unit.span)),
-            _ => Err(ShellError::CantConvert("unit value".into(), e.span)),
+            x => Err(ShellError::CantConvert(
+                "unit value".into(),
+                x.get_type().to_string(),
+                e.span,
+            )),
         },
         Expr::Range(from, next, to, operator) => {
             let from = if let Some(f) = from {
@@ -224,7 +228,10 @@ pub fn eval_expression(
         Expr::RowCondition(_, expr) => eval_expression(engine_state, stack, expr),
         Expr::Call(call) => {
             // FIXME: protect this collect with ctrl-c
-            Ok(eval_call(engine_state, stack, call, PipelineData::new())?.into_value())
+            Ok(
+                eval_call(engine_state, stack, call, PipelineData::new(call.head))?
+                    .into_value(call.head),
+            )
         }
         Expr::ExternalCall(name, span, args) => {
             // FIXME: protect this collect with ctrl-c
@@ -234,10 +241,10 @@ pub fn eval_expression(
                 name,
                 span,
                 args,
-                PipelineData::new(),
+                PipelineData::new(*span),
                 true,
             )?
-            .into_value())
+            .into_value(*span))
         }
         Expr::Operator(_) => Ok(Value::Nothing { span: expr.span }),
         Expr::BinaryOp(lhs, op, rhs) => {
@@ -271,7 +278,10 @@ pub fn eval_expression(
             let block = engine_state.get_block(*block_id);
 
             // FIXME: protect this collect with ctrl-c
-            Ok(eval_block(engine_state, stack, block, PipelineData::new())?.into_value())
+            Ok(
+                eval_subexpression(engine_state, stack, block, PipelineData::new(expr.span))?
+                    .into_value(expr.span),
+            )
         }
         Expr::Block(block_id) => Ok(Value::Block {
             val: *block_id,
@@ -370,6 +380,64 @@ pub fn eval_block(
     Ok(input)
 }
 
+pub fn eval_subexpression(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    block: &Block,
+    mut input: PipelineData,
+) -> Result<PipelineData, ShellError> {
+    for stmt in block.stmts.iter() {
+        if let Statement::Pipeline(pipeline) = stmt {
+            for (i, elem) in pipeline.expressions.iter().enumerate() {
+                match elem {
+                    Expression {
+                        expr: Expr::Call(call),
+                        ..
+                    } => {
+                        input = eval_call(engine_state, stack, call, input)?;
+                    }
+                    Expression {
+                        expr: Expr::ExternalCall(name, name_span, args),
+                        ..
+                    } => {
+                        input = eval_external(
+                            engine_state,
+                            stack,
+                            name,
+                            name_span,
+                            args,
+                            input,
+                            false,
+                        )?;
+
+                        if i == pipeline.expressions.len() - 1 {
+                            // We're at the end, so drain as a string for the value
+                            // to be used later
+                            // FIXME: the trimming of the end probably needs to live in a better place
+
+                            let mut s = input.collect_string();
+                            if s.ends_with('\n') {
+                                s.pop();
+                            }
+                            input = Value::String {
+                                val: s.to_string(),
+                                span: *name_span,
+                            }
+                            .into_pipeline_data()
+                        }
+                    }
+
+                    elem => {
+                        input = eval_expression(engine_state, stack, elem)?.into_pipeline_data();
+                    }
+                }
+            }
+        }
+    }
+
+    Ok(input)
+}
+
 pub fn eval_variable(
     engine_state: &EngineState,
     stack: &Stack,

crates/nu-engine/src/from_value.rs

@@ -32,7 +32,11 @@ impl FromValue for Spanned<i64> {
                 span: *span,
             }),
 
-            v => Err(ShellError::CantConvert("integer".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "integer".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -44,7 +48,11 @@ impl FromValue for i64 {
             Value::Filesize { val, .. } => Ok(*val as i64),
             Value::Duration { val, .. } => Ok(*val as i64),
 
-            v => Err(ShellError::CantConvert("integer".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "integer".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -61,7 +69,11 @@ impl FromValue for Spanned<f64> {
                 span: *span,
             }),
 
-            v => Err(ShellError::CantConvert("float".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "float".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -71,7 +83,11 @@ impl FromValue for f64 {
         match v {
             Value::Float { val, .. } => Ok(*val),
             Value::Int { val, .. } => Ok(*val as f64),
-            v => Err(ShellError::CantConvert("float".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "float".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -109,7 +125,11 @@ impl FromValue for CellPath {
                     span,
                 }],
             }),
-            _ => Err(ShellError::CantConvert("cell path".into(), span)),
+            x => Err(ShellError::CantConvert(
+                "cell path".into(),
+                x.get_type().to_string(),
+                span,
+            )),
         }
     }
 }
@@ -118,7 +138,11 @@ impl FromValue for bool {
     fn from_value(v: &Value) -> Result<Self, ShellError> {
         match v {
             Value::Bool { val, .. } => Ok(*val),
-            v => Err(ShellError::CantConvert("bool".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "bool".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -130,7 +154,11 @@ impl FromValue for Spanned<bool> {
                 item: *val,
                 span: *span,
             }),
-            v => Err(ShellError::CantConvert("bool".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "bool".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -139,7 +167,11 @@ impl FromValue for DateTime<FixedOffset> {
     fn from_value(v: &Value) -> Result<Self, ShellError> {
         match v {
             Value::Date { val, .. } => Ok(*val),
-            v => Err(ShellError::CantConvert("date".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "date".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -151,7 +183,11 @@ impl FromValue for Spanned<DateTime<FixedOffset>> {
                 item: *val,
                 span: *span,
             }),
-            v => Err(ShellError::CantConvert("date".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "date".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -160,7 +196,11 @@ impl FromValue for Range {
     fn from_value(v: &Value) -> Result<Self, ShellError> {
         match v {
             Value::Range { val, .. } => Ok((**val).clone()),
-            v => Err(ShellError::CantConvert("range".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "range".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -172,7 +212,11 @@ impl FromValue for Spanned<Range> {
                 item: (**val).clone(),
                 span: *span,
             }),
-            v => Err(ShellError::CantConvert("range".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "range".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }
@@ -182,7 +226,11 @@ impl FromValue for Vec<u8> {
         match v {
             Value::Binary { val, .. } => Ok(val.clone()),
             Value::String { val, .. } => Ok(val.bytes().collect()),
-            v => Err(ShellError::CantConvert("binary data".into(), v.span()?)),
+            v => Err(ShellError::CantConvert(
+                "binary data".into(),
+                v.get_type().to_string(),
+                v.span()?,
+            )),
         }
     }
 }

crates/nu-parser/src/parser.rs

@@ -1292,6 +1292,7 @@ pub fn parse_full_cell_path(
     if let Some(head) = tokens.peek() {
         let bytes = working_set.get_span_contents(head.span);
         let (head, expect_dot) = if bytes.starts_with(b"(") {
+            let head_span = head.span;
             let mut start = head.span.start;
             let mut end = head.span.end;
 
@@ -1331,7 +1332,7 @@ pub fn parse_full_cell_path(
             (
                 Expression {
                     expr: Expr::Subexpression(block_id),
-                    span,
+                    span: head_span,
                     ty: Type::Unknown, // FIXME
                     custom_completion: None,
                 },

crates/nu-protocol/src/pipeline_data.rs

@@ -37,16 +37,16 @@ pub enum PipelineData {
 }
 
 impl PipelineData {
-    pub fn new() -> PipelineData {
-        PipelineData::Value(Value::nothing())
+    pub fn new(span: Span) -> PipelineData {
+        PipelineData::Value(Value::Nothing { span })
     }
 
-    pub fn into_value(self) -> Value {
+    pub fn into_value(self, span: Span) -> Value {
         match self {
             PipelineData::Value(v) => v,
             PipelineData::Stream(s) => Value::List {
                 vals: s.collect(),
-                span: Span::unknown(), // FIXME?
+                span, // FIXME?
             },
         }
     }
@@ -140,11 +140,11 @@ impl PipelineData {
     }
 }
 
-impl Default for PipelineData {
-    fn default() -> Self {
-        PipelineData::new()
-    }
-}
+// impl Default for PipelineData {
+//     fn default() -> Self {
+//         PipelineData::new()
+//     }
+// }
 
 pub struct PipelineIterator(PipelineData);
 

crates/nu-protocol/src/shell_error.rs

@@ -82,7 +82,7 @@ pub enum ShellError {
 
     #[error("Can't convert to {0}.")]
     #[diagnostic(code(nu::shell::cant_convert), url(docsrs))]
-    CantConvert(String, #[label("can't convert to {0}")] Span),
+    CantConvert(String, String, #[label("can't convert {1} to {0}")] Span),
 
     #[error("Division by zero.")]
     #[diagnostic(code(nu::shell::division_by_zero), url(docsrs))]

crates/nu-protocol/src/value/mod.rs

@@ -87,7 +87,14 @@ impl Value {
     pub fn as_string(&self) -> Result<String, ShellError> {
         match self {
             Value::String { val, .. } => Ok(val.to_string()),
-            _ => Err(ShellError::CantConvert("string".into(), self.span()?)),
+            x => {
+                println!("{:?}", x);
+                Err(ShellError::CantConvert(
+                    "string".into(),
+                    x.get_type().to_string(),
+                    self.span()?,
+                ))
+            }
         }
     }
 
@@ -225,10 +232,8 @@ impl Value {
     }
 
     /// Create a new `Nothing` value
-    pub fn nothing() -> Value {
-        Value::Nothing {
-            span: Span::unknown(),
-        }
+    pub fn nothing(span: Span) -> Value {
+        Value::Nothing { span }
     }
 
     /// Follow a given column path into the value: for example accessing nth elements in a stream or list
@@ -425,7 +430,9 @@ impl Value {
 
 impl Default for Value {
     fn default() -> Self {
-        Value::nothing()
+        Value::Nothing {
+            span: Span::unknown(),
+        }
     }
 }
 

src/main.rs

@@ -19,7 +19,7 @@ use nu_parser::parse;
 use nu_protocol::{
     ast::Call,
     engine::{EngineState, Stack, StateWorkingSet},
-    IntoPipelineData, PipelineData, ShellError, Value,
+    IntoPipelineData, PipelineData, ShellError, Span, Value,
 };
 use reedline::{Completer, CompletionActionHandler, DefaultPrompt, LineBuffer, Prompt};
 
@@ -126,7 +126,12 @@ fn main() -> Result<()> {
             stack.env_vars.insert(k, v);
         }
 
-        match eval_block(&engine_state, &mut stack, &block, PipelineData::new()) {
+        match eval_block(
+            &engine_state,
+            &mut stack,
+            &block,
+            PipelineData::new(Span::unknown()),
+        ) {
             Ok(pipeline_data) => {
                 println!("{}", pipeline_data.collect_string());
             }
@@ -312,7 +317,12 @@ fn update_prompt<'prompt>(
 
     let mut stack = stack.clone();
 
-    let evaluated_prompt = match eval_block(engine_state, &mut stack, &block, PipelineData::new()) {
+    let evaluated_prompt = match eval_block(
+        engine_state,
+        &mut stack,
+        &block,
+        PipelineData::new(Span::unknown()),
+    ) {
         Ok(pipeline_data) => pipeline_data.collect_string(),
         Err(err) => {
             let working_set = StateWorkingSet::new(engine_state);
@@ -349,9 +359,14 @@ fn eval_source(
 
     engine_state.merge_delta(delta);
 
-    match eval_block(engine_state, stack, &block, PipelineData::new()) {
+    match eval_block(
+        engine_state,
+        stack,
+        &block,
+        PipelineData::new(Span::unknown()),
+    ) {
         Ok(pipeline_data) => {
-            if let Err(err) = print_value(pipeline_data.into_value(), engine_state) {
+            if let Err(err) = print_value(pipeline_data.into_value(Span::unknown()), engine_state) {
                 let working_set = StateWorkingSet::new(engine_state);
 
                 report_error(&working_set, &err);