1 files changed, 20 insertions, 3 deletions
diff --git a/src/checker_signature.rs b/src/checker_signature.rs
index 8fc982a..4fa723f 100644
--- a/src/checker_signature.rs
+++ b/src/checker_signature.rs
@@ -6,8 +6,25 @@ use tracing::instrument;
 impl CheckerState {
     #[instrument(skip(self), level = "debug", fields(%signature))]
     pub fn check_signature(&self, signature: Signature) -> Result<Signature, CheckerError> {
-        Err(CheckerError::Unimplemented(
-            "signature checking".to_string(),
-        ))
+        match signature {
+            Signature::Set => Ok(Signature::Set),
+            Signature::Var(v) => {
+                let deref = self.lookup_signature(&v)?;
+                Ok(deref.clone())
+            }
+            Signature::Ext { params, codomain } => Err(CheckerError::Unimplemented(
+                "extension signatures".to_string(),
+            )),
+            Signature::Theory(fields) => {
+                let fields = fields
+                    .into_iter()
+                    .map(|SigField { signature, name }| {
+                        let signature = self.check_signature(signature)?;
+                        Ok(SigField { name, signature })
+                    })
+                    .collect::<Result<Vec<_>, _>>()?;
+                Ok(Signature::Theory(fields))
+            }
+        }
     }
 }