1 files changed, 57 insertions, 0 deletions
diff --git a/vere/pkg/noun/jets/a/dec.c b/vere/pkg/noun/jets/a/dec.c
new file mode 100644
index 0000000..02a8ba1
--- /dev/null
+++ b/vere/pkg/noun/jets/a/dec.c
@@ -0,0 +1,57 @@
+/// @file
+
+#include "jets/k.h"
+#include "jets/q.h"
+#include "jets/w.h"
+
+#include "noun.h"
+
+u3_noun
+u3qa_inc(u3_atom a)
+{
+  return u3i_vint(u3k(a));
+}
+
+u3_noun
+u3qa_dec(u3_atom a)
+{
+  if ( 0 == a ) {
+    return u3m_error("decrement-underflow");
+  }
+  else {
+    if ( _(u3a_is_cat(a)) ) {
+      return a - 1;
+    }
+    else {
+      mpz_t a_mp;
+
+      u3r_mp(a_mp, a);
+      mpz_sub_ui(a_mp, a_mp, 1);
+
+      return u3i_mp(a_mp);
+    }
+  }
+}
+
+u3_noun
+u3wa_dec(u3_noun cor)
+{
+  u3_noun a;
+
+  if ( (u3_none == (a = u3r_at(u3x_sam, cor))) ||
+       (c3n == u3ud(a)) )
+  {
+    return u3m_bail(c3__fail);
+  }
+  else {
+    return u3qa_dec(a);
+  }
+}
+
+u3_noun
+u3ka_dec(u3_atom a)
+{
+  u3_noun b = u3qa_dec(a);
+  u3z(a);
+  return b;
+}