1 files changed, 46 insertions, 0 deletions
diff --git a/vere/pkg/noun/jets/d/by_jab.c b/vere/pkg/noun/jets/d/by_jab.c
new file mode 100644
index 0000000..7468adc
--- /dev/null
+++ b/vere/pkg/noun/jets/d/by_jab.c
@@ -0,0 +1,46 @@
+/// @file
+
+#include "jets/q.h"
+#include "jets/w.h"
+
+#include "noun.h"
+
+u3_noun
+u3qdb_jab(u3_noun a,
+          u3_noun key,
+          u3_noun fun)
+{
+  if ( u3_nul == a ) {
+    return u3m_bail(c3__exit);
+  }
+  else {
+    u3_noun n_a, lr_a;
+    u3_noun pn_a, qn_a;
+    u3x_cell(a, &n_a, &lr_a);
+    u3x_cell(n_a, &pn_a, &qn_a);
+
+    if ( (c3y == u3r_sing(key, pn_a)) ) {
+      u3_noun value = u3n_slam_on(u3k(fun), u3k(qn_a));
+      return u3nc(u3nc(u3k(pn_a), value), u3k(u3t(a)));
+    }
+    else {
+      u3_noun l_a, r_a;
+      u3x_cell(lr_a, &l_a, &r_a);
+
+      return ( c3y == u3qc_gor(key, pn_a) )
+             ? u3nt(u3k(n_a), u3qdb_jab(l_a, key, fun), u3k(r_a))
+             : u3nt(u3k(n_a), u3k(l_a), u3qdb_jab(r_a, key, fun));
+    }
+  }
+}
+
+u3_noun
+u3wdb_jab(u3_noun cor)
+{
+  u3_noun a, key, fun;
+  u3x_mean(cor, u3x_sam_2,   &key,
+                u3x_sam_3,   &fun,
+                u3x_con_sam, &a, 0);
+
+  return u3qdb_jab(a, key, fun);
+}