diff --git a/compiler/erg_compiler/ty/free.rs b/compiler/erg_compiler/ty/free.rs
index cc7da214..e465ccb4 100644
--- a/compiler/erg_compiler/ty/free.rs
+++ b/compiler/erg_compiler/ty/free.rs
@@ -255,14 +255,18 @@ impl<T: LimitedDisplay> LimitedDisplay for FreeKind<T> {
                 constraint,
             } => {
                 if *lev == GENERIC_LEVEL {
-                    write!(f, "{name}(")?;
-                    constraint.limited_fmt(f, limit - 1)?;
-                    write!(f, ")")?;
-                } else {
-                    write!(f, "?{name}(")?;
-                    constraint.limited_fmt(f, limit - 1)?;
-                    write!(f, ")")?;
+                    write!(f, "{name}")?;
                     if cfg!(feature = "debug") {
+                        write!(f, "(")?;
+                        constraint.limited_fmt(f, limit - 1)?;
+                        write!(f, ")")?;
+                    }
+                } else {
+                    write!(f, "?{name}")?;
+                    if cfg!(feature = "debug") {
+                        write!(f, "(")?;
+                        constraint.limited_fmt(f, limit - 1)?;
+                        write!(f, ")")?;
                         write!(f, "[{lev}]")?;
                     }
                 }
@@ -274,14 +278,18 @@ impl<T: LimitedDisplay> LimitedDisplay for FreeKind<T> {
                 constraint,
             } => {
                 if *lev == GENERIC_LEVEL {
-                    write!(f, "%{id}(")?;
-                    constraint.limited_fmt(f, limit - 1)?;
-                    write!(f, ")")?;
-                } else {
-                    write!(f, "?{id}(")?;
-                    constraint.limited_fmt(f, limit - 1)?;
-                    write!(f, ")")?;
+                    write!(f, "%{id}")?;
                     if cfg!(feature = "debug") {
+                        write!(f, "(")?;
+                        constraint.limited_fmt(f, limit - 1)?;
+                        write!(f, ")")?;
+                    }
+                } else {
+                    write!(f, "?{id}")?;
+                    if cfg!(feature = "debug") {
+                        write!(f, "(")?;
+                        constraint.limited_fmt(f, limit - 1)?;
+                        write!(f, ")")?;
                         write!(f, "[{lev}]")?;
                     }
                 }
diff --git a/compiler/erg_compiler/ty/mod.rs b/compiler/erg_compiler/ty/mod.rs
index 9e63146a..4759c070 100644
--- a/compiler/erg_compiler/ty/mod.rs
+++ b/compiler/erg_compiler/ty/mod.rs
@@ -1192,7 +1192,7 @@ impl LimitedDisplay for Type {
                 write!(f, "|")?;
                 for (i, (name, constr)) in qvars.iter().enumerate() {
                     if i != 0 {
-                        write!(f, "; ")?;
+                        write!(f, ", ")?;
                     }
                     write!(f, "{name}")?;
                     constr.limited_fmt(f, limit - 1)?;