Warning: This is the manual of the legacy Guile 2.2 series. You may want to read the manual of the current stable series instead.

9.2.5.5 Heap Cell Type Information

Heap cells contain a number of entries, each of which is either a scheme object of type SCM or a raw C value of type scm_t_bits. Which of the cell entries contain Scheme objects and which contain raw C values is determined by the first entry of the cell, which holds the cell type information.

Macro: scm_t_bits SCM_CELL_TYPE (SCM x)

For a non-immediate Scheme object x, deliver the content of the first entry of the heap cell referenced by x. This value holds the information about the cell type.

Macro: void SCM_SET_CELL_TYPE (SCM x, scm_t_bits t)

For a non-immediate Scheme object x, write the value t into the first entry of the heap cell referenced by x. The value t must hold a valid cell type.