From c8fe1c2fdb8d3124fbd03ea3ee399f8bfc76a516 Mon Sep 17 00:00:00 2001
From: Giacomo Cavalieri <giacomo.cavalieri@icloud.com>
Date: Mon, 7 Oct 2024 15:19:03 +0200
Subject: [PATCH] Define untyped echo

---
 compiler-core/src/ast/untyped.rs      |  6 ++++++
 compiler-core/src/ast_folder.rs       | 24 ++++++++++++++++++++++++
 compiler-core/src/call_graph.rs       |  9 +++++++++
 compiler-core/src/format.rs           | 12 ++++++++++++
 compiler-core/src/type_/expression.rs | 23 +++++++++++++++++++++++
 5 files changed, 74 insertions(+)

diff --git a/compiler-core/src/ast/untyped.rs b/compiler-core/src/ast/untyped.rs
index f5407ffee98..2cea0218506 100644
--- a/compiler-core/src/ast/untyped.rs
+++ b/compiler-core/src/ast/untyped.rs
@@ -106,6 +106,11 @@ pub enum UntypedExpr {
         message: Option<Box<Self>>,
     },
 
+    Echo {
+        location: SrcSpan,
+        expression: Option<Box<Self>>,
+    },
+
     BitArray {
         location: SrcSpan,
         segments: Vec<UntypedExprBitArraySegment>,
@@ -148,6 +153,7 @@ impl UntypedExpr {
             | Self::Var { location, .. }
             | Self::Int { location, .. }
             | Self::Todo { location, .. }
+            | Self::Echo { location, .. }
             | Self::Case { location, .. }
             | Self::Call { location, .. }
             | Self::List { location, .. }
diff --git a/compiler-core/src/ast_folder.rs b/compiler-core/src/ast_folder.rs
index 1f731403dfd..07ddf7d4008 100644
--- a/compiler-core/src/ast_folder.rs
+++ b/compiler-core/src/ast_folder.rs
@@ -312,6 +312,11 @@ pub trait UntypedExprFolder: TypeAstFolder + UntypedConstantFolder + PatternFold
                 message,
             } => self.fold_todo(kind, location, message),
 
+            UntypedExpr::Echo {
+                location,
+                expression,
+            } => self.fold_echo(location, expression),
+
             UntypedExpr::Panic { location, message } => self.fold_panic(location, message),
 
             UntypedExpr::BitArray { location, segments } => self.fold_bit_array(location, segments),
@@ -357,6 +362,14 @@ pub trait UntypedExprFolder: TypeAstFolder + UntypedConstantFolder + PatternFold
                 message: message.map(|msg_expr| Box::new(self.fold_expr(*msg_expr))),
             },
 
+            UntypedExpr::Echo {
+                location,
+                expression,
+            } => UntypedExpr::Echo {
+                location,
+                expression: expression.map(|expression| Box::new(self.fold_expr(*expression))),
+            },
+
             UntypedExpr::Block {
                 location,
                 statements,
@@ -783,6 +796,17 @@ pub trait UntypedExprFolder: TypeAstFolder + UntypedConstantFolder + PatternFold
         }
     }
 
+    fn fold_echo(
+        &mut self,
+        location: SrcSpan,
+        expression: Option<Box<UntypedExpr>>,
+    ) -> UntypedExpr {
+        UntypedExpr::Echo {
+            location,
+            expression,
+        }
+    }
+
     fn fold_panic(&mut self, location: SrcSpan, message: Option<Box<UntypedExpr>>) -> UntypedExpr {
         UntypedExpr::Panic { location, message }
     }
diff --git a/compiler-core/src/call_graph.rs b/compiler-core/src/call_graph.rs
index 91944ec1a3b..d61881e6e70 100644
--- a/compiler-core/src/call_graph.rs
+++ b/compiler-core/src/call_graph.rs
@@ -179,6 +179,15 @@ impl<'a> CallGraphBuilder<'a> {
                 }
             }
 
+            UntypedExpr::Echo {
+                expression,
+                location: _,
+            } => {
+                if let Some(expression) = expression {
+                    self.expression(expression);
+                }
+            }
+
             // Aha! A variable is being referenced.
             UntypedExpr::Var { name, .. } => {
                 self.referenced(name);
diff --git a/compiler-core/src/format.rs b/compiler-core/src/format.rs
index 1c8e249d757..f5e1bf8f0be 100644
--- a/compiler-core/src/format.rs
+++ b/compiler-core/src/format.rs
@@ -911,6 +911,16 @@ impl<'comments> Formatter<'comments> {
                 message: Some(l), ..
             } => docvec!["todo as ", self.expr(l)],
 
+            UntypedExpr::Echo {
+                expression: None,
+                location: _,
+            } => "echo".to_doc(),
+
+            UntypedExpr::Echo {
+                expression: Some(e),
+                location: _,
+            } => docvec!["echo ", self.expr(e)],
+
             UntypedExpr::PipeLine { expressions, .. } => self.pipeline(expressions, false),
 
             UntypedExpr::Int { value, .. } => self.int(value),
@@ -1178,6 +1188,7 @@ impl<'comments> Formatter<'comments> {
             | UntypedExpr::Tuple { .. }
             | UntypedExpr::TupleIndex { .. }
             | UntypedExpr::Todo { .. }
+            | UntypedExpr::Echo { .. }
             | UntypedExpr::Panic { .. }
             | UntypedExpr::BitArray { .. }
             | UntypedExpr::RecordUpdate { .. }
@@ -2446,6 +2457,7 @@ impl<'comments> Formatter<'comments> {
             | UntypedExpr::TupleIndex { .. }
             | UntypedExpr::Todo { .. }
             | UntypedExpr::Panic { .. }
+            | UntypedExpr::Echo { .. }
             | UntypedExpr::BitArray { .. }
             | UntypedExpr::RecordUpdate { .. }
             | UntypedExpr::NegateBool { .. }
diff --git a/compiler-core/src/type_/expression.rs b/compiler-core/src/type_/expression.rs
index 0785f72710e..56ac8c77220 100644
--- a/compiler-core/src/type_/expression.rs
+++ b/compiler-core/src/type_/expression.rs
@@ -306,6 +306,11 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
                 location, message, ..
             } => self.infer_panic(location, message),
 
+            UntypedExpr::Echo {
+                location,
+                expression,
+            } => self.infer_echo(location, expression),
+
             UntypedExpr::Var { location, name, .. } => self.infer_var(name, location),
 
             UntypedExpr::Int {
@@ -465,6 +470,24 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
         })
     }
 
+    fn infer_echo(
+        &mut self,
+        location: SrcSpan,
+        expression: Option<Box<UntypedExpr>>,
+    ) -> Result<TypedExpr, Error> {
+        if let Some(expression) = expression {
+            let typed_expression = self.infer(*expression);
+            Ok(todo!("typed expr ECHO"))
+        } else {
+            todo!(
+                "
+echo with no expression after it
+should only be in a pipeline
+"
+            )
+        }
+    }
+
     pub(crate) fn warn_for_unreachable_code(
         &mut self,
         location: SrcSpan,