WIP

crates/nu-protocol/src/ast/block.rs

@@ -1,9 +1,12 @@
 use std::ops::{Index, IndexMut};
 
+use crate::Signature;
+
 use super::Statement;
 
 #[derive(Debug, Clone)]
 pub struct Block {
+    pub signature: Box<Signature>,
     pub stmts: Vec<Statement>,
 }
 
@@ -39,6 +42,9 @@ impl Default for Block {
 
 impl Block {
     pub fn new() -> Self {
-        Self { stmts: vec![] }
+        Self {
+            signature: Box::new(Signature::new("")),
+            stmts: vec![],
+        }
     }
 }

crates/nu-protocol/src/engine/command.rs

@@ -50,8 +50,8 @@ pub trait Command {
         false
     }
 
-    // If command is a custom command i.e. def blah [] { }, get the block id
-    fn get_custom_command(&self) -> Option<BlockId> {
+    // If command is a block i.e. def blah [] { }, get the block id
+    fn get_block_id(&self) -> Option<BlockId> {
         None
     }
 }

crates/nu-protocol/src/shell_error.rs

@@ -1,6 +1,6 @@
-use crate::{Span, Type};
+use crate::{ast::Operator, Span, Type};
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum ShellError {
     OperatorMismatch {
         op_span: Span,
@@ -9,7 +9,9 @@ pub enum ShellError {
         rhs_ty: Type,
         rhs_span: Span,
     },
-    Unsupported(Span),
+    UnsupportedOperator(Operator, Span),
+    UnknownOperator(String, Span),
+    ExternalNotSupported(Span),
     InternalError(String),
     VariableNotFound(Span),
     CantConvert(String, Span),

crates/nu-protocol/src/signature.rs

@@ -350,7 +350,7 @@ impl Command for BlockCommand {
     }
 
     fn signature(&self) -> Signature {
-        self.signature.clone()
+        panic!("Internal error: can't get signature with 'signature', use block_id");
     }
 
     fn usage(&self) -> &str {
@@ -366,7 +366,7 @@ impl Command for BlockCommand {
         panic!("Internal error: can't run custom command with 'run', use block_id");
     }
 
-    fn get_custom_command(&self) -> Option<BlockId> {
+    fn get_block_id(&self) -> Option<BlockId> {
         Some(self.block_id)
     }
 }

crates/nu-protocol/src/ty.rs

@@ -19,6 +19,7 @@ pub enum Type {
     RowStream,
     ValueStream,
     Unknown,
+    Error,
 }
 
 impl Display for Type {
@@ -41,6 +42,7 @@ impl Display for Type {
             Type::ValueStream => write!(f, "value stream"),
             Type::RowStream => write!(f, "row stream"),
             Type::Unknown => write!(f, "unknown"),
+            Type::Error => write!(f, "error"),
         }
     }
 }

crates/nu-protocol/src/value.rs

@@ -158,6 +158,9 @@ pub enum Value {
     Nothing {
         span: Span,
     },
+    Error {
+        err: ShellError,
+    },
 }
 
 impl Value {
@@ -181,6 +184,7 @@ impl Value {
             Value::RowStream { span, .. } => *span,
             Value::ValueStream { span, .. } => *span,
             Value::Nothing { span, .. } => *span,
+            Value::Error { .. } => Span::unknown(),
         }
     }
 
@@ -197,6 +201,7 @@ impl Value {
             Value::Table { span, .. } => *span = new_span,
             Value::Block { span, .. } => *span = new_span,
             Value::Nothing { span, .. } => *span = new_span,
+            Value::Error { .. } => {}
         }
 
         self
@@ -215,6 +220,7 @@ impl Value {
             Value::Block { .. } => Type::Block,
             Value::ValueStream { .. } => Type::ValueStream,
             Value::RowStream { .. } => Type::RowStream,
+            Value::Error { .. } => Type::Error,
         }
     }
 
@@ -264,6 +270,7 @@ impl Value {
             } => stream.into_string(headers),
             Value::Block { val, .. } => format!("<Block {}>", val),
             Value::Nothing { .. } => String::new(),
+            Value::Error { err } => format!("{:?}", err),
         }
     }