urbit/j/e/tape.c
2015-02-10 15:13:17 -08:00

56 lines
815 B
C

/* j/3/tape.c
**
*/
#include "all.h"
/* functions
*/
static u3_noun
_norm(
u3_noun a)
{
if ( c3n == u3du(a) ) {
return u3_nul;
} else {
return u3nc(((c3y == u3du(u3h(a))) ? u3_nul : u3k(u3h(a))),
_norm(u3t(a)));
}
}
static u3_noun
_good(
u3_noun a)
{
while ( 1 ) {
if ( u3_nul == a ) {
return c3y;
}
if ( c3n == u3ud(u3h(a)) ) {
return c3n;
}
a = u3t(a);
}
}
u3_noun
u3qe_tape(u3_noun a)
{
if ( c3y == _good(a) ) {
return u3k(a);
} else {
return _norm(a);
}
}
u3_noun
u3we_tape(u3_noun cor)
{
u3_noun a;
if ( (u3_none == (a = u3r_at(u3x_sam, cor))) ) {
return u3m_bail(c3__fail);
} else {
return u3qe_tape(a);
}
}