add is_mergeable

.gitignore

@@ -20,3 +20,4 @@
 /tests/vm/*.out
 .DS_Store
 .idea/
+.vscode/

kevm-pyk/src/kevm_pyk/kevm.py

@@ -224,6 +224,24 @@ def can_make_custom_step(self, cterm: CTerm) -> bool:
         load_pattern = KSequence([KApply('loadProgram', KVariable('###BYTECODE')), KVariable('###CONTINUATION')])
         self._cached_subst = load_pattern.match(cterm.cell('K_CELL'))
         return self._cached_subst is not None
+
+    def is_mergeable(self, ct1: CTerm, ct2: CTerm) -> bool:
+        """Given two CTerms of Edges' targets, check if they are mergeable.
+        
+        Two CTerms are mergeable if their `STATUSCODE_CELL` and `PROGRAM_CELL` are the same.
+        If mergeable, the two corresponding Edges are merged into one.
+
+        :param ct1: CTerm of one Edge's target.
+        :param ct2: CTerm of another Edge's target.
+        :return: `True` if the two CTerms are mergeable; `False` otherwise.
+        """
+        status_code_1 = ct1.cell('STATUSCODE_CELL')
+        status_code_2 = ct2.cell('STATUSCODE_CELL')
+        program_1 = ct1.cell('PROGRAM_CELL')
+        program_2 = ct2.cell('PROGRAM_CELL')
+        if type(status_code_1) is KApply and type(status_code_2) is KApply and type(program_1) is KToken and type(program_2) is KToken:
+            return status_code_1 == status_code_2 and program_1 == program_2
+        raise ValueError(f'Attempted to merge nodes with non-concrete <statusCode> or <program>: {(ct1, ct2)}')
 
 
 class KEVM(KProve, KRun):