diff --git a/runner/src/ast.rs b/runner/src/ast.rs
index f0ad2891f..a58e06c22 100644
--- a/runner/src/ast.rs
+++ b/runner/src/ast.rs
@@ -6,14 +6,14 @@ use std::{
 #[derive(Debug, Clone)]
 pub enum Expr {
     Value(String),
-    Array(Vec<String>),
+    Array(Vec<Expr>),
 }
 
 impl Display for Expr {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Expr::Value(v) => write!(f, "{}", v),
-            Expr::Array(v) => write!(f, "{:?}", v),
+            Expr::Value(v) => write!(f, "{v}"),
+            Expr::Array(v) => write!(f, "{v:?}"),
         }
     }
 }
@@ -29,7 +29,7 @@ impl Display for Exprs {
             if i != 0 {
                 write!(f, ", ")?;
             }
-            write!(f, "{}", expr)?;
+            write!(f, "{expr}")?;
         }
 
         write!(f, "]")?;
diff --git a/runner/src/parser.lalrpop b/runner/src/parser.lalrpop
index f79958ff2..daa655768 100644
--- a/runner/src/parser.lalrpop
+++ b/runner/src/parser.lalrpop
@@ -7,20 +7,15 @@ pub CairoParserOutput: Exprs = {
     StructName "(" <n:Comma<Arg>> ")" => Exprs(n.iter().flat_map(|x| x.iter().cloned()).collect()),
 };
 
-FlatExpr: Vec<String> = {
-    <n:Num> => vec![n],
-    StructName "()" => Vec::new(),
-    StructName "(" <n:Comma<FlatArg>> ")" => n.iter().flat_map(|x| x.iter().cloned()).collect(),
-};
-
-FlatArg: Vec<String> = {
-    ArgName "=" <n:FlatExpr> => n,
+CairoParserOutputInner: Exprs = {
+    <n:Num> => Exprs(vec![Expr::Value(n)]),
+    "[" <n:Comma<CairoParserOutputInner>> "]" => Exprs(vec![Expr::Array(n.iter().flat_map(|x| x.iter().cloned()).collect())]),
+    StructName "()" => Exprs(Vec::new()),
+    StructName "(" <n:Comma<Arg>> ")" => Exprs(n.iter().flat_map(|x| x.iter().cloned()).collect()),
 };
 
 Arg: Exprs = {
-    ArgName "=" <n:Num> => Exprs(vec![Expr::Value(n)]),
-    ArgName "=" "[" <n:Comma<FlatExpr>> "]" => Exprs(vec![Expr::Array(n.iter().flat_map(|x| x.iter().cloned()).collect())]),
-    ArgName "=" <n:CairoParserOutput> => n,
+    ArgName "=" <n:CairoParserOutputInner> => n,
 };
 
 Comma<T>: Vec<T> = {