feat(prolog): Atom unification

src/prolog/Result.kt

@@ -0,0 +1,5 @@
+package prolog
+
+import prolog.terms.Variable
+
+data class Result(val success: Boolean, val substitutions: List<Variable>)

src/prolog/terms/Atom.kt

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+package prolog.terms
+
+data class Atom(val name: String): Term()

src/prolog/terms/Term.kt

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+package prolog.terms
+
+sealed class Term

src/prolog/unify.kt

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+package prolog
+
+import prolog.terms.Term
+
+fun unify(term1: Term, term2: Term): Result {
+    return Result(term1 == term2, emptyList())
+}

tests/prolog/unifyTest.kt

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+package prolog
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import prolog.terms.Atom
+
+class unifyTest {
+    @Test
+    fun identical_atoms_unify() {
+        val atom1 = Atom("a")
+        val atom2 = Atom("a")
+
+        val result = unify(atom1, atom2)
+
+        assertTrue(result.success)
+        assertEquals(0, result.substitutions.size)
+    }
+
+    @Test
+    fun different_atoms_do_not_unify() {
+        val atom1 = Atom("a")
+        val atom2 = Atom("b")
+
+        val result = unify(atom1, atom2)
+
+        assertFalse(result.success)
+        assertEquals(0, result.substitutions.size)
+    }
+}