stdin

typedef enum {
  INTEGER,
  FLOAT,
  CHAR,
  STRING,
  SYMBOL,
  LIST,
  LPAREN,
  RPAREN,
  QUOTED,
} type_t;

typedef enum {
  NIL,
  UNDEFINED,
  //etc...
} builtin_t;

/*Here's what an object looks like:*/
typedef struct {
  type_t type;
  union value {
    int64_t integer;
    double float;
    char *string;
    builtin_t builtin;
    void *void;
  }
} object_t;