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authorVsevolod Stakhov <vsevolod@highsecure.ru>2015-02-16 16:35:18 +0000
committerVsevolod Stakhov <vsevolod@highsecure.ru>2015-02-16 16:35:18 +0000
commit195bfd320c83a04728faf213b38346b18b28d5a0 (patch)
tree3600a6b395ee6b403d4cc869b7ff45b08958384a /contrib
parent858dd01f283427ba7554de1ccebbbf5eec18aaf3 (diff)
downloadrspamd-195bfd320c83a04728faf213b38346b18b28d5a0.tar.gz
rspamd-195bfd320c83a04728faf213b38346b18b28d5a0.zip
Import lua-functional for plugins stuff.
Diffstat (limited to 'contrib')
-rw-r--r--contrib/lua-fun/COPYING.md27
-rw-r--r--contrib/lua-fun/fun.lua968
2 files changed, 995 insertions, 0 deletions
diff --git a/contrib/lua-fun/COPYING.md b/contrib/lua-fun/COPYING.md
new file mode 100644
index 000000000..42ee231eb
--- /dev/null
+++ b/contrib/lua-fun/COPYING.md
@@ -0,0 +1,27 @@
+Copying
+=======
+
+**Lua Fun** source codes, logo and documentation are distributed under the
+**[MIT/X11 License]** - same as Lua and LuaJIT.
+
+Copyright (c) 2013 Roman Tsisyk <roman@tsisyk.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+[MIT/X11 License]: http://www.opensource.org/licenses/mit-license.php
diff --git a/contrib/lua-fun/fun.lua b/contrib/lua-fun/fun.lua
new file mode 100644
index 000000000..5d019d6a1
--- /dev/null
+++ b/contrib/lua-fun/fun.lua
@@ -0,0 +1,968 @@
+---
+--- Lua Fun - a high-performance functional programming library for LuaJIT
+---
+--- Copyright (c) 2013 Roman Tsisyk <roman@tsisyk.com>
+---
+--- Distributed under the MIT/X11 License. See COPYING.md for more details.
+---
+
+--------------------------------------------------------------------------------
+-- Tools
+--------------------------------------------------------------------------------
+
+local return_if_not_empty = function(state_x, ...)
+ if state_x == nil then
+ return nil
+ end
+ return ...
+end
+
+local call_if_not_empty = function(fun, state_x, ...)
+ if state_x == nil then
+ return nil
+ end
+ return state_x, fun(...)
+end
+
+local function deepcopy(orig) -- used by cycle()
+ local orig_type = type(orig)
+ local copy
+ if orig_type == 'table' then
+ copy = {}
+ for orig_key, orig_value in next, orig, nil do
+ copy[deepcopy(orig_key)] = deepcopy(orig_value)
+ end
+ else
+ copy = orig
+ end
+ return copy
+end
+
+--------------------------------------------------------------------------------
+-- Basic Functions
+--------------------------------------------------------------------------------
+
+local nil_gen = function(_param, _state)
+ return nil
+end
+
+local string_gen = function(param, state)
+ local state = state + 1
+ if state > #param then
+ return nil
+ end
+ local r = string.sub(param, state, state)
+ return state, r
+end
+
+local pairs_gen = pairs({ a = 0 }) -- get the generating function from pairs
+local map_gen = function(tab, key)
+ local value
+ local key, value = pairs_gen(tab, key)
+ return key, key, value
+end
+
+local iter = function(obj, param, state)
+ assert(obj ~= nil, "invalid iterator")
+ if (type(obj) == "function") then
+ return obj, param, state
+ elseif (type(obj) == "table" or type(obj) == "userdata") then
+ if #obj > 0 then
+ return ipairs(obj)
+ else
+ return map_gen, obj, nil
+ end
+ elseif (type(obj) == "string") then
+ if #obj == 0 then
+ return nil_gen, nil, nil
+ end
+ return string_gen, obj, 0
+ end
+ error(string.format('object %s of type "%s" is not iterable',
+ obj, type(obj)))
+end
+
+local iter_tab = function(obj)
+ if type(obj) == "function" then
+ return obj, nil, nil
+ elseif type(obj) == "table" and type(obj[1]) == "function" then
+ return obj[1], obj[2], obj[3]
+ else
+ return iter(obj)
+ end
+end
+
+local each = function(fun, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ repeat
+ state_x = call_if_not_empty(fun, gen_x(param_x, state_x))
+ until state_x == nil
+end
+
+--------------------------------------------------------------------------------
+-- Generators
+--------------------------------------------------------------------------------
+
+local range_gen = function(param, state)
+ local stop, step = param[1], param[2]
+ local state = state + step
+ if state >= stop then
+ return nil
+ end
+ return state, state
+end
+
+local range_rev_gen = function(param, state)
+ local stop, step = param[1], param[2]
+ local state = state + step
+ if state <= stop then
+ return nil
+ end
+ return state, state
+end
+
+local range = function(start, stop, step)
+ if step == nil then
+ step = 1
+ if stop == nil then
+ stop = start
+ start = 0
+ end
+ end
+
+ assert(type(start) == "number", "start must be a number")
+ assert(type(stop) == "number", "stop must be a number")
+ assert(type(step) == "number", "step must be a number")
+ assert(step ~= 0, "step must not be zero")
+
+ if (step > 0) then
+ return range_gen, {stop, step}, start - step
+ elseif (step < 0) then
+ return range_rev_gen, {stop, step}, start - step
+ end
+end
+
+local duplicate_table_gen = function(param_x, state_x)
+ return state_x + 1, unpack(param_x)
+end
+
+local duplicate_fun_gen = function(param_x, state_x)
+ return state_x + 1, param_x(state_x)
+end
+
+local duplicate_gen = function(param_x, state_x)
+ return state_x + 1, param_x
+end
+
+local duplicate = function(...)
+ if select('#', ...) <= 1 then
+ return duplicate_gen, select(1, ...), 0
+ else
+ return duplicate_table_gen, {...}, 0
+ end
+end
+
+local tabulate = function(fun)
+ assert(type(fun) == "function")
+ return duplicate_fun_gen, fun, 0
+end
+
+local zeros = function()
+ return duplicate_gen, 0, 0
+end
+
+local ones = function()
+ return duplicate_gen, 1, 0
+end
+
+local rands_gen = function(param_x, _state_x)
+ return 0, math.random(param_x[1], param_x[2])
+end
+
+local rands_nil_gen = function(_param_x, _state_x)
+ return 0, math.random()
+end
+
+local rands = function(n, m)
+ if n == nil and m == nil then
+ return rands_nil_gen, 0, 0
+ end
+ assert(type(n) == "number", "invalid first arg to rands")
+ if m == nil then
+ m = n
+ n = 0
+ else
+ assert(type(m) == "number", "invalid second arg to rands")
+ end
+ assert(n < m, "empty interval")
+ return rands_gen, {n, m - 1}, 0
+end
+
+--------------------------------------------------------------------------------
+-- Slicing
+--------------------------------------------------------------------------------
+
+local nth = function(n, gen, param, state)
+ assert(n > 0, "invalid first argument to nth")
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ -- An optimization for arrays and strings
+ if gen_x == ipairs then
+ return param_x[n]
+ elseif gen_x == string_gen then
+ if n < #param_x then
+ return string.sub(param_x, n, n)
+ else
+ return nil
+ end
+ end
+ for i=1,n-1,1 do
+ state_x = gen_x(param_x, state_x)
+ if state_x == nil then
+ return nil
+ end
+ end
+ return return_if_not_empty(gen_x(param_x, state_x))
+end
+
+local head_call = function(state, ...)
+ if state == nil then
+ error("head: iterator is empty")
+ end
+ return ...
+end
+
+local head = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return head_call(gen_x(param_x, state_x))
+end
+
+local tail = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ state_x = gen_x(param_x, state_x)
+ if state_x == nil then
+ return nil_gen, nil, nil
+ end
+ return gen_x, param_x, state_x
+end
+
+local take_n_gen_x = function(i, state_x, ...)
+ if state_x == nil then
+ return nil
+ end
+ return {i, state_x}, ...
+end
+
+local take_n_gen = function(param, state)
+ local n, gen_x, param_x = param[1], param[2], param[3]
+ local i, state_x = state[1], state[2]
+ if i >= n then
+ return nil
+ end
+ return take_n_gen_x(i + 1, gen_x(param_x, state_x))
+end
+
+local take_n = function(n, gen, param, state)
+ assert(n >= 0, "invalid first argument to take_n")
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return take_n_gen, {n, gen, param}, {0, state}
+end
+
+local take_while_gen_x = function(fun, state_x, ...)
+ if state_x == nil or not fun(...) then
+ return nil
+ end
+ return state_x, ...
+end
+
+local take_while_gen = function(param, state_x)
+ local fun, gen_x, param_x = param[1], param[2], param[3]
+ return take_while_gen_x(fun, gen_x(param_x, state_x))
+end
+
+local take_while = function(fun, gen, param, state)
+ assert(type(fun) == "function", "invalid first argument to take_while")
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return take_while_gen, {fun, gen, param}, state
+end
+
+local take = function(n_or_fun, gen, param, state)
+ if type(n_or_fun) == "number" then
+ return take_n(n_or_fun, gen, param, state)
+ else
+ return take_while(n_or_fun, gen, param, state)
+ end
+end
+
+local drop_n = function(n, gen, param, state)
+ assert(n >= 0, "invalid first argument to drop_n")
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ for i=1,n,1 do
+ state_x = gen_x(param_x, state_x)
+ if state_x == nil then
+ return nil_gen, nil, nil
+ end
+ end
+ return gen_x, param_x, state_x
+end
+
+local drop_while_x = function(fun, state_x, ...)
+ if state_x == nil or not fun(...) then
+ return state_x, false
+ end
+ return state_x, true, ...
+end
+
+local drop_while = function(fun, gen, param, state)
+ assert(type(fun) == "function", "invalid first argument to drop_while")
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local cont, state_x_prev
+ repeat
+ state_x_prev = deepcopy(state_x)
+ state_x, cont = drop_while_x(fun, gen_x(param_x, state_x))
+ until not cont
+ if state_x == nil then
+ return nil_gen, nil, nil
+ end
+ return gen_x, param_x, state_x_prev
+end
+
+local drop = function(n_or_fun, gen, param, state)
+ if type(n_or_fun) == "number" then
+ return drop_n(n_or_fun, gen, param, state)
+ else
+ return drop_while(n_or_fun, gen, param, state)
+ end
+end
+
+local split = function(n_or_fun, gen, param, state)
+ return {take(n_or_fun, gen, param, state)},
+ {drop(n_or_fun, gen, param, state)}
+end
+
+--------------------------------------------------------------------------------
+-- Indexing
+--------------------------------------------------------------------------------
+
+local index = function(x, gen, param, state)
+ local i = 1
+ for _k, r in iter(gen, param, state) do
+ if r == x then
+ return i
+ end
+ i = i + 1
+ end
+ return nil
+end
+
+local indexes_gen = function(param, state)
+ local x, gen_x, param_x = param[1], param[2], param[3]
+ local i, state_x = state[1], state[2]
+ local r
+ while true do
+ state_x, r = gen_x(param_x, state_x)
+ if state_x == nil then
+ return nil
+ end
+ i = i + 1
+ if r == x then
+ return {i, state_x}, i
+ end
+ end
+end
+
+local indexes = function(x, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return indexes_gen, {x, gen_x, param_x}, {0, state_x}
+end
+
+-- TODO: undocumented
+local find = function(fun, gen, param, state)
+ local gen_x, param_x, state_x = filter(fun, gen, param, state)
+ return return_if_not_empty(gen_x(param_x, state_x))
+end
+
+--------------------------------------------------------------------------------
+-- Filtering
+--------------------------------------------------------------------------------
+
+local filter1_gen = function(fun, gen_x, param_x, state_x, a)
+ while true do
+ if state_x == nil or fun(a) then break; end
+ state_x, a = gen_x(param_x, state_x)
+ end
+ return state_x, a
+end
+
+-- call each other
+local filterm_gen
+local filterm_gen_shrink = function(fun, gen_x, param_x, state_x)
+ return filterm_gen(fun, gen_x, param_x, gen_x(param_x, state_x))
+end
+
+filterm_gen = function(fun, gen_x, param_x, state_x, ...)
+ if state_x == nil then
+ return nil
+ end
+ if fun(...) then
+ return state_x, ...
+ end
+ return filterm_gen_shrink(fun, gen_x, param_x, state_x)
+end
+
+local filter_detect = function(fun, gen_x, param_x, state_x, ...)
+ if select('#', ...) < 2 then
+ return filter1_gen(fun, gen_x, param_x, state_x, ...)
+ else
+ return filterm_gen(fun, gen_x, param_x, state_x, ...)
+ end
+end
+
+local filter_gen = function(param, state_x)
+ local fun, gen_x, param_x = param[1], param[2], param[3]
+ return filter_detect(fun, gen_x, param_x, gen_x(param_x, state_x))
+end
+
+local filter = function(fun, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return filter_gen, {fun, gen_x, param_x}, state_x
+end
+
+local grep = function(fun_or_regexp, gen, param, state)
+ local fun = fun_or_regexp
+ if type(fun_or_regexp) == "string" then
+ fun = function(x) return string.find(x, fun_or_regexp) ~= nil end
+ end
+ return filter(fun, gen, param, state)
+end
+
+local partition = function(fun, gen, param, state)
+ local neg_fun = function(...)
+ return not fun(...)
+ end
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return {filter(fun, gen_x, param_x, state_x)},
+ {filter(neg_fun, gen_x, param_x, state_x)}
+end
+
+--------------------------------------------------------------------------------
+-- Reducing
+--------------------------------------------------------------------------------
+
+local foldl_call = function(fun, start, state, ...)
+ if state == nil then
+ return nil, start
+ end
+ return state, fun(start, ...)
+end
+
+local foldl = function(fun, start, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ while true do
+ state_x, start = foldl_call(fun, start, gen_x(param_x, state_x))
+ if state_x == nil then
+ break;
+ end
+ end
+ return start
+end
+
+local length = function(gen, param, state)
+ local gen, param, state = iter(gen, param, state)
+ if gen == ipairs or gen == string_gen then
+ return #param
+ end
+ local len = 0
+ repeat
+ state = gen(param, state)
+ len = len + 1
+ until state == nil
+ return len - 1
+end
+
+local is_null = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return gen_x(param_x, deepcopy(state_x)) == nil
+end
+
+local is_prefix_of = function(iter_x, iter_y)
+ local gen_x, param_x, state_x = iter_tab(iter_x)
+ local gen_y, param_y, state_y = iter_tab(iter_y)
+
+ local r_x, r_y
+ for i=1,10,1 do
+ state_x, r_x = gen_x(param_x, state_x)
+ state_y, r_y = gen_y(param_y, state_y)
+ if state_x == nil then
+ return true
+ end
+ if state_y == nil or r_x ~= r_y then
+ return false
+ end
+ end
+end
+
+local all = function(fun, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local r
+ repeat
+ state_x, r = call_if_not_empty(fun, gen_x(param_x, state_x))
+ until state_x == nil or not r
+ return state_x == nil
+end
+
+local any = function(fun, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local r
+ repeat
+ state_x, r = call_if_not_empty(fun, gen_x(param_x, state_x))
+ until state_x == nil or r
+ return not not r
+end
+
+local sum = function(gen, param, state)
+ local gen, param, state = iter(gen, param, state)
+ local s = 0
+ local r = 0
+ repeat
+ s = s + r
+ state, r = gen(param, state)
+ until state == nil
+ return s
+end
+
+local product = function(gen, param, state)
+ local gen, param, state = iter(gen, param, state)
+ local p = 1
+ local r = 1
+ repeat
+ p = p * r
+ state, r = gen(param, state)
+ until state == nil
+ return p
+end
+
+local min_cmp = function(m, n)
+ if n < m then return n else return m end
+end
+
+local max_cmp = function(m, n)
+ if n > m then return n else return m end
+end
+
+local min = function(gen, param, state)
+ local gen, param, state = iter(gen, param, state)
+ local state, m = gen(param, state)
+ if state == nil then
+ error("min: iterator is empty")
+ end
+
+ local cmp
+ if type(m) == "number" then
+ -- An optimization: use math.min for numbers
+ cmp = math.min
+ else
+ cmp = min_cmp
+ end
+
+ for _, r in gen, param, state do
+ m = cmp(m, r)
+ end
+ return m
+end
+
+local min_by = function(cmp, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local state_x, m = gen_x(param_x, state_x)
+ if state_x == nil then
+ error("min: iterator is empty")
+ end
+
+ for _, r in gen_x, param_x, state_x do
+ m = cmp(m, r)
+ end
+ return m
+end
+
+local max = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local state_x, m = gen_x(param_x, state_x)
+ if state_x == nil then
+ error("max: iterator is empty")
+ end
+
+ local cmp
+ if type(m) == "number" then
+ -- An optimization: use math.max for numbers
+ cmp = math.max
+ else
+ cmp = max_cmp
+ end
+
+ for _, r in gen_x, param_x, state_x do
+ m = cmp(m, r)
+ end
+ return m
+end
+
+local max_by = function(cmp, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local state_x, m = gen_x(param_x, state_x)
+ if state_x == nil then
+ error("max: iterator is empty")
+ end
+
+ for _, r in gen_x, param_x, state_x do
+ m = cmp(m, r)
+ end
+ return m
+end
+
+local totable = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local tab, key, val = {}
+ while true do
+ state_x, val = gen_x(param_x, state_x)
+ if state_x == nil then
+ break
+ end
+ table.insert(tab, val)
+ end
+ return tab
+end
+
+local tomap = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ local tab, key, val = {}
+ while true do
+ state_x, key, val = gen_x(param_x, state_x)
+ if state_x == nil then
+ break
+ end
+ tab[key] = val
+ end
+ return tab
+end
+
+--------------------------------------------------------------------------------
+-- Transformations
+--------------------------------------------------------------------------------
+
+local map_gen = function(param, state)
+ local gen_x, param_x, fun = param[1], param[2], param[3]
+ return call_if_not_empty(fun, gen_x(param_x, state))
+end
+
+local map = function(fun, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return map_gen, {gen_x, param_x, fun}, state_x
+end
+
+local enumerate_gen_call = function(state, i, state_x, ...)
+ if state_x == nil then
+ return nil
+ end
+ return {i + 1, state_x}, i, ...
+end
+
+local enumerate_gen = function(param, state)
+ local gen_x, param_x = param[1], param[2]
+ local i, state_x = state[1], state[2]
+ return enumerate_gen_call(state, i, gen_x(param_x, state_x))
+end
+
+local enumerate = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return enumerate_gen, {gen_x, param_x}, {0, state_x}
+end
+
+local intersperse_call = function(i, state_x, ...)
+ if state_x == nil then
+ return nil
+ end
+ return {i + 1, state_x}, ...
+end
+
+local intersperse_gen = function(param, state)
+ local x, gen_x, param_x = param[1], param[2], param[3]
+ local i, state_x = state[1], state[2]
+ if i % 2 == 1 then
+ return {i + 1, state_x}, x
+ else
+ return intersperse_call(i, gen_x(param_x, state_x))
+ end
+end
+
+-- TODO: interperse must not add x to the tail
+local intersperse = function(x, gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return intersperse_gen, {x, gen_x, param_x}, {0, state_x}
+end
+
+--------------------------------------------------------------------------------
+-- Compositions
+--------------------------------------------------------------------------------
+
+local function zip_gen_r(param, state, state_new, ...)
+ if #state_new == #param / 2 then
+ return state_new, ...
+ end
+
+ local i = #state_new + 1
+ local gen_x, param_x = param[2 * i - 1], param[2 * i]
+ local state_x, r = gen_x(param_x, state[i])
+ -- print('i', i, 'state_x', state_x, 'r', r)
+ if state_x == nil then
+ return nil
+ end
+ table.insert(state_new, state_x)
+ return zip_gen_r(param, state, state_new, r, ...)
+end
+
+local zip_gen = function(param, state)
+ return zip_gen_r(param, state, {})
+end
+
+local zip = function(...)
+ local n = select('#', ...)
+ if n == 0 then
+ return nil_gen, nil, nil
+ end
+ local param = { [2 * n] = 0 }
+ local state = { [n] = 0 }
+
+ local i, gen_x, param_x, state_x
+ for i=1,n,1 do
+ local elem = select(n - i + 1, ...)
+ gen_x, param_x, state_x = iter_tab(elem)
+ param[2 * i - 1] = gen_x
+ param[2 * i] = param_x
+ state[i] = state_x
+ end
+
+ return zip_gen, param, state
+end
+
+local cycle_gen_call = function(param, state_x, ...)
+ if state_x == nil then
+ local gen_x, param_x, state_x0 = param[1], param[2], param[3]
+ return gen_x(param_x, deepcopy(state_x0))
+ end
+ return state_x, ...
+end
+
+local cycle_gen = function(param, state_x)
+ local gen_x, param_x, state_x0 = param[1], param[2], param[3]
+ return cycle_gen_call(param, gen_x(param_x, state_x))
+end
+
+local cycle = function(gen, param, state)
+ local gen_x, param_x, state_x = iter(gen, param, state)
+ return cycle_gen, {gen_x, param_x, state_x}, deepcopy(state_x)
+end
+
+-- call each other
+local chain_gen_r1
+local chain_gen_r2 = function(param, state, state_x, ...)
+ if state_x == nil then
+ local i = state[1]
+ i = i + 1
+ if i > #param / 3 then
+ return nil
+ end
+ local state_x = param[3 * i]
+ return chain_gen_r1(param, {i, state_x})
+ end
+ return {state[1], state_x}, ...
+end
+
+chain_gen_r1 = function(param, state)
+ local i, state_x = state[1], state[2]
+ local gen_x, param_x = param[3 * i - 2], param[3 * i - 1]
+ return chain_gen_r2(param, state, gen_x(param_x, state[2]))
+end
+
+local chain = function(...)
+ local n = select('#', ...)
+ if n == 0 then
+ return nil_gen, nil, nil
+ end
+
+ local param = { [3 * n] = 0 }
+ local i, gen_x, param_x, state_x
+ for i=1,n,1 do
+ local elem = select(i, ...)
+ gen_x, param_x, state_x = iter_tab(elem)
+ param[3 * i - 2] = gen_x
+ param[3 * i - 1] = param_x
+ param[3 * i] = state_x
+ end
+
+ return chain_gen_r1, param, {1, param[3]}
+end
+
+--------------------------------------------------------------------------------
+-- Operators
+--------------------------------------------------------------------------------
+
+operator = {
+ ----------------------------------------------------------------------------
+ -- Comparison operators
+ ----------------------------------------------------------------------------
+ lt = function(a, b) return a < b end,
+ le = function(a, b) return a <= b end,
+ eq = function(a, b) return a == b end,
+ ne = function(a, b) return a ~= b end,
+ ge = function(a, b) return a >= b end,
+ gt = function(a, b) return a > b end,
+
+ ----------------------------------------------------------------------------
+ -- Arithmetic operators
+ ----------------------------------------------------------------------------
+ add = function(a, b) return a + b end,
+ div = function(a, b) return a / b end,
+ floordiv = function(a, b) return math.floor(a/b) end,
+ intdiv = function(a, b)
+ local q = a / b
+ if a >= 0 then return math.floor(q) else return math.ceil(q) end
+ end,
+ mod = function(a, b) return a % b end,
+ mul = function(a, b) return a * b end,
+ neq = function(a) return -a end,
+ unm = function(a) return -a end, -- an alias
+ pow = function(a, b) return a ^ b end,
+ sub = function(a, b) return a - b end,
+ truediv = function(a, b) return a / b end,
+
+ ----------------------------------------------------------------------------
+ -- String operators
+ ----------------------------------------------------------------------------
+ concat = function(a, b) return a..b end,
+ len = function(a) return #a end,
+ length = function(a) return #a end, -- an alias
+
+ ----------------------------------------------------------------------------
+ -- Logical operators
+ ----------------------------------------------------------------------------
+ land = function(a, b) return a and b end,
+ lor = function(a, b) return a or b end,
+ lnot = function(a) return not a end,
+ truth = function(a) return not not a end,
+}
+
+--------------------------------------------------------------------------------
+-- module definitions
+--------------------------------------------------------------------------------
+
+local exports = {
+ ----------------------------------------------------------------------------
+ -- Basic
+ ----------------------------------------------------------------------------
+ iter = iter,
+ each = each,
+ for_each = each, -- an alias
+ foreach = each, -- an alias
+
+ ----------------------------------------------------------------------------
+ -- Generators
+ ----------------------------------------------------------------------------
+ range = range,
+ duplicate = duplicate,
+ xrepeat = duplicate, -- an alias
+ replicate = duplicate, -- an alias
+ tabulate = tabulate,
+ ones = ones,
+ zeros = zeros,
+ rands = rands,
+
+ ----------------------------------------------------------------------------
+ -- Slicing
+ ----------------------------------------------------------------------------
+ nth = nth,
+ head = head,
+ car = head, -- an alias
+ tail = tail,
+ cdr = tail, -- an alias
+ take_n = take_n,
+ take_while = take_while,
+ take = take,
+ drop_n = drop_n,
+ drop_while = drop_while,
+ drop = drop,
+ split = split,
+ split_at = split, -- an alias
+ span = split, -- an alias
+
+ ----------------------------------------------------------------------------
+ -- Indexing
+ ----------------------------------------------------------------------------
+ index = index,
+ index_of = index, -- an alias
+ elem_index = index, -- an alias
+ indexes = indexes,
+ indices = indexes, -- an alias
+ elem_indexes = indexes, -- an alias
+ elem_indices = indexes, -- an alias
+ find = find,
+
+ ----------------------------------------------------------------------------
+ -- Filtering
+ ----------------------------------------------------------------------------
+ filter = filter,
+ remove_if = filter, -- an alias
+ grep = grep,
+ partition = partition,
+
+ ----------------------------------------------------------------------------
+ -- Reducing
+ ----------------------------------------------------------------------------
+ foldl = foldl,
+ reduce = foldl, -- an alias
+ length = length,
+ is_null = is_null,
+ is_prefix_of = is_prefix_of,
+ all = all,
+ every = all, -- an alias
+ any = any,
+ some = any, -- an alias
+ sum = sum,
+ product = product,
+ min = min,
+ minimum = min, -- an alias
+ min_by = min_by,
+ minimum_by = min_by, -- an alias
+ max = max,
+ maximum = max, -- an alias
+ max_by = max_by,
+ maximum_by = max_by, -- an alias
+ totable = totable,
+ tomap = tomap,
+
+ ----------------------------------------------------------------------------
+ -- Transformations
+ ----------------------------------------------------------------------------
+ map = map,
+ enumerate = enumerate,
+ intersperse = intersperse,
+
+ ----------------------------------------------------------------------------
+ -- Compositions
+ ----------------------------------------------------------------------------
+ zip = zip,
+ cycle = cycle,
+ chain = chain,
+
+ ----------------------------------------------------------------------------
+ -- Operators
+ ----------------------------------------------------------------------------
+ operator = operator,
+ op = operator -- an alias
+}
+
+-- a special syntax sugar to export all functions to the global table
+setmetatable(exports, {
+ __call = function(t)
+ for k, v in pairs(t) do _G[k] = v end
+ end,
+})
+
+return exports