From 38a716d94eae49c7c6ec25fb5cea7d78ed629ebc Mon Sep 17 00:00:00 2001
From: rvcas <x@rvcas.dev>
Date: Fri, 23 Dec 2022 15:47:54 -0500
Subject: [PATCH] feat: allow error to hold a label

---
 crates/aiken-lang/src/air.rs       |  1 +
 crates/aiken-lang/src/expr.rs      |  2 ++
 crates/aiken-lang/src/parser.rs    | 11 +++++++++--
 crates/aiken-lang/src/tipo/expr.rs | 12 +++++++++---
 crates/aiken-lang/src/uplc.rs      | 21 +++++++++++++++++++--
 5 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/crates/aiken-lang/src/air.rs b/crates/aiken-lang/src/air.rs
index 4ad55444..cb1b67d0 100644
--- a/crates/aiken-lang/src/air.rs
+++ b/crates/aiken-lang/src/air.rs
@@ -205,6 +205,7 @@ pub enum Air {
     ErrorTerm {
         scope: Vec<u64>,
         tipo: Arc<Type>,
+        label: Option<String>,
     },
 
     Trace {
diff --git a/crates/aiken-lang/src/expr.rs b/crates/aiken-lang/src/expr.rs
index 530ec438..3b14b287 100644
--- a/crates/aiken-lang/src/expr.rs
+++ b/crates/aiken-lang/src/expr.rs
@@ -151,6 +151,7 @@ pub enum TypedExpr {
     ErrorTerm {
         location: Span,
         tipo: Arc<Type>,
+        label: Option<String>,
     },
 
     RecordUpdate {
@@ -425,6 +426,7 @@ pub enum UntypedExpr {
 
     ErrorTerm {
         location: Span,
+        label: Option<String>,
     },
 
     RecordUpdate {
diff --git a/crates/aiken-lang/src/parser.rs b/crates/aiken-lang/src/parser.rs
index 68806090..84a1f35a 100644
--- a/crates/aiken-lang/src/parser.rs
+++ b/crates/aiken-lang/src/parser.rs
@@ -852,8 +852,15 @@ pub fn expr_parser(
             });
 
         let error_parser = just(Token::ErrorTerm)
-            .ignored()
-            .map_with_span(|_, span| expr::UntypedExpr::ErrorTerm { location: span });
+            .ignore_then(
+                select! {Token::String {value} => value}
+                    .delimited_by(just(Token::LeftParen), just(Token::RightParen))
+                    .or_not(),
+            )
+            .map_with_span(|label, span| expr::UntypedExpr::ErrorTerm {
+                location: span,
+                label,
+            });
 
         let tuple = just(Token::Hash)
             .ignore_then(
diff --git a/crates/aiken-lang/src/tipo/expr.rs b/crates/aiken-lang/src/tipo/expr.rs
index 95c47feb..ffafd25f 100644
--- a/crates/aiken-lang/src/tipo/expr.rs
+++ b/crates/aiken-lang/src/tipo/expr.rs
@@ -236,7 +236,9 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
                 ..
             } => Ok(self.infer_todo(location, kind, label)),
 
-            UntypedExpr::ErrorTerm { location } => Ok(self.infer_error_term(location)),
+            UntypedExpr::ErrorTerm { location, label } => {
+                Ok(self.infer_error_term(location, label))
+            }
 
             UntypedExpr::Var { location, name, .. } => self.infer_var(name, location),
 
@@ -1761,10 +1763,14 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
         }
     }
 
-    fn infer_error_term(&mut self, location: Span) -> TypedExpr {
+    fn infer_error_term(&mut self, location: Span, label: Option<String>) -> TypedExpr {
         let tipo = self.new_unbound_var();
 
-        TypedExpr::ErrorTerm { location, tipo }
+        TypedExpr::ErrorTerm {
+            location,
+            tipo,
+            label,
+        }
     }
 
     fn infer_trace(
diff --git a/crates/aiken-lang/src/uplc.rs b/crates/aiken-lang/src/uplc.rs
index 77ec8941..263e439e 100644
--- a/crates/aiken-lang/src/uplc.rs
+++ b/crates/aiken-lang/src/uplc.rs
@@ -537,10 +537,11 @@ impl<'a> CodeGenerator<'a> {
                 todo!("Tuple indexing not implementing yet");
             }
 
-            TypedExpr::ErrorTerm { tipo, .. } => {
+            TypedExpr::ErrorTerm { tipo, label, .. } => {
                 ir_stack.push(Air::ErrorTerm {
                     scope,
                     tipo: tipo.clone(),
+                    label: label.clone(),
                 });
             }
         }
@@ -3739,7 +3740,23 @@ impl<'a> CodeGenerator<'a> {
 
                 arg_stack.push(term);
             }
-            Air::ErrorTerm { .. } => arg_stack.push(Term::Error),
+            Air::ErrorTerm { label, .. } => {
+                if let Some(label) = label {
+                    let term = Term::Apply {
+                        function: Term::Apply {
+                            function: Term::Builtin(DefaultFunction::Trace).force_wrap().into(),
+                            argument: Term::Constant(UplcConstant::String(label)).into(),
+                        }
+                        .into(),
+                        argument: Term::Delay(Term::Error.into()).into(),
+                    }
+                    .force_wrap();
+
+                    arg_stack.push(term);
+                } else {
+                    arg_stack.push(Term::Error)
+                }
+            }
         }
     }
 }