Heap objects contain a type tag and are followed by a number of word-sized slots. The interpretation of the object contents depends on the type of the object.
Extract the first word of the heap object pointed to by x. This value holds the information about the cell type.
(SCM x, scm_t_bits t)¶
For a non-immediate Scheme object x, write the value t into the first word of the heap object referenced by x. The value t must hold a valid cell type.