molly: propagate luafun iterators

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Allow chaining `luafun` iterators with iterators defined in Molly and vice versa.
 - Using of SQL prepared statements in test examples.
 
 ### Removed

molly/gen.lua

@@ -40,32 +40,13 @@ local fun = require('fun')
 local clock = require('molly.clock')
 local log = require('molly.log')
 
-local methods = {}
-local exports = {}
-
-local iterator_mt = {
-    __call = function(self, param, state)
-        return self.gen(param, state)
-    end,
-    __index = methods,
-    __tostring = function(self)
-        return '<generator>'
-    end
-}
-
-local wrap = function(gen, param, state)
-    return setmetatable({
-        gen = gen,
-        param = param,
-        state = state
-    }, iterator_mt), param, state
-end
-exports.wrap = wrap
+local fun_mt = debug.getmetatable(fun.range(10))
+local methods = fun_mt.__index
+local exports = table.copy(fun)
 
 local unwrap = function(self)
     return self.gen, self.param, self.state
 end
-methods.unwrap = unwrap
 
 -- Helpers
 
@@ -652,7 +633,7 @@ end)(function(timeout, gen, param, state)
     local get_time = clock.monotonic
     local start_time = get_time()
     local time_is_exceed = false
-    return wrap(function(ctx, state_x)
+    return fun.wrap(function(ctx, state_x)
         local gen_x, param_x, duration, cnt = ctx[1], ctx[2], ctx[3], ctx[4] + 1
         ctx[4] = cnt
         if time_is_exceed == false then