urbit/jets/b/roll.c
2018-10-03 11:57:18 -04:00

46 lines
806 B
C

/* j/2/roll.c
**
*/
#include "all.h"
static u3_noun
_roll_in(u3j_site* sit_u, u3_noun a, u3_noun b)
{
if ( 0 == a ) {
return b;
}
else if ( c3n == u3du(a) ) {
return u3m_bail(c3__exit);
}
else {
b = u3j_gate_slam(sit_u, u3nc(u3k(u3h(a)), b));
return _roll_in(sit_u, u3t(a), b);
}
}
/* functions
*/
u3_noun
u3qb_roll(u3_noun a,
u3_noun b)
{
u3_noun pro;
u3j_site sit_u;
u3j_gate_prep(&sit_u, u3k(b));
pro = _roll_in(&sit_u, a, u3k(u3x_at(u3x_sam_3, b)));
u3j_gate_lose(&sit_u);
return pro;
}
u3_noun
u3wb_roll(u3_noun cor)
{
u3_noun a, b;
if ( c3n == u3r_mean(cor, u3x_sam_2, &a, u3x_sam_3, &b, 0) ) {
return u3m_bail(c3__exit);
} else {
return u3qb_roll(a, b);
}
}