stdlib: scaffold ets ffi

Works on #8

Author: leostera

src/stdlib/beam/stdlib_ets.ml

@@ -0,0 +1,27 @@
+type ('k, 'v) tid
+
+type table_type = [ `Set | `Ordered_set | `Bag | `Duplicate_bag ]
+
+type access = [ `Public | `Protected | `Private ]
+
+type concurrency = [ `Write_concurrency of bool | `Read_concurrency of bool ]
+
+type make_opt =
+  [ access
+  | concurrency
+  | table_type
+  | `Named_table
+  | `Decentralized_counters of bool
+  | `Compressed ]
+
+external make : 'a -> make_opt list -> ('k, 'v) tid = "new"
+
+external lookup : ('k, 'v) tid -> 'k -> 'v list = ""
+
+external insert_one : ('k, 'v) tid -> 'k * 'v -> unit = "insert"
+
+external insert_many : ('k, 'v) tid -> ('k * 'v) list -> unit = "insert"
+
+external foldl : ('k * 'v -> 'acc -> 'acc) -> 'acc -> ('k, 'v) tid -> 'acc = ""
+
+external foldr : ('k * 'v -> 'acc -> 'acc) -> 'acc -> ('k, 'v) tid -> 'acc = ""