Give an event locals

LOCAL_LOAD and LOCAL_STORE name one of an event's 64 slots, what it holds
(a number, or an index of a list) and that list: slots start at 0 when an
event begins, are shared by its handlers, the walks in them and the folds
in those, and are never saved nor in the states' namespace. A handler uses
a slot for one thing, so its type is verified as a state's is; views have
no locals (IN_LOCALS: a handler's block, a walk in it, a fold in either;
stores only in a handler and its walks). A fold reading a local still runs
a leaf at a time (one value for every item) and a shaped fold takes one
only on its key's side. The signature table's where widens to 16 bits.

locals checks a handler that sums items into a local in a walk, counts in
a fold the items below it, keeps an index in a local and reads it back,
over 80 events against a model, and five refusals. server_rows' shop now
takes stock through an index local and counts in one.

1 files changed, 8 insertions, 0 deletions

diff --git a/core/module.h b/core/module.h
index 0b20a9f..b8f8e98 100644
--- a/core/module.h
+++ b/core/module.h
@@ -39,8 +39,16 @@ typedef enum {
     PURE_OP_INDEX_MOVE, PURE_OP_INDEX_FIRST, PURE_OP_INDEX_LAST, PURE_OP_INDEX_NUM, PURE_OP_ROW,
     PURE_OP_PICK, PURE_OP_SLIDE, PURE_OP_FOLD, PURE_OP_TEXT_COMPARE, PURE_OP_LIST_FIND, PURE_OP_LIST_HAS,
     PURE_OP_NOW, PURE_OP_FLOOR, PURE_OP_MOD, PURE_OP_SEND, PURE_OP_OUTER_ROW, PURE_OP_EACH,
+    PURE_OP_LOCAL_LOAD, PURE_OP_LOCAL_STORE,
     PURE_OP_COUNT
 } PureOpcode;
+/* A local: one of an event's PURE_MODULE_LOCALS slots, 0 when the event
+ * begins and never saved. LOCAL_LOAD and LOCAL_STORE name the slot (bits
+ * 0-7), what it holds (bits 8-15: 0 a number, 1 an index) and an index's
+ * list (bits 16-31); a handler uses a slot for one of them. A handler, the
+ * walks in it and the folds in those read locals; the handler and its walks
+ * store them. */
+enum { PURE_MODULE_LOCALS = 64 };
 /* EACH's argument: the list state (bits 8-15) and the length of the block
  * that follows (16-31), run in a handler once for every item the list had
  * when it began, in order, with ROW the item; the block may change states,