feat: added Drop trait

drop.c

@@ -0,0 +1,6 @@
+#include "drop.h"
+#include "stdlib.h"
+
+void default_drop(void* data) {
+    free(data);
+}

drop.h

@@ -0,0 +1,33 @@
+#ifndef _fencer_drop_h
+#define _fencer_drop_h
+
+#include "typeclass_helpers.h"
+
+typedef struct {
+    void (*const drop)(void* self);
+} IDrop;
+
+typedef struct {
+    void* data;
+    IDrop const* tc;
+} Drop;
+
+#define impl_Drop_for(T, drop_f)\
+Drop T##_as_Drop(T* x) {\
+    TC_FN_TYPECHECK(void, drop_f, T*);\
+    static IDrop const tc = {\
+        .drop = (void(*const)(void*)) drop_f,\
+    };\
+    return (Drop){.tc = &tc, .data = x};\
+}
+
+extern void default_drop(void*);
+
+#define impl_default_Drop_for(T)\
+Drop T##_as_Drop(T* x) {\
+    static IDrop const tc = {\
+        .drop = default_drop,\
+    };\
+    return (Drop){.tc = &tc, .data = x};\
+}
+#endif // !_fencer_drop_h