-- sequence adapters

local seq = require 'pl.seq'

-- can't directly look these up in seq because of the wrong argument order...
local overrides = {
	map = function(self,fun)
		return seq.map(fun,self)
	end,
	reduce = function(self,fun)
		return seq.reduce(fun,self)
	end
}

SMT = {
	__index = function (tbl,key)
		local s = overrides[key] or seq[key]
		if s then
			return function(sw,...) return SW(s(sw.iter,...)) end
		else
			return function(sw,...) return SW(seq.mapmethod(sw.iter,key,...)) end
		end
	end,
	__call = function (sw)
		return sw.iter()
	end,
}

function callable (v)
    return type(v) == 'function' or getmetatable(v) and getmetatable(v).__call
end

function S (iter)
	if not callable(iter) then
		if type(iter) == 'table' then iter = seq.list(iter)
		else return iter
		end
	end
	return setmetatable({iter=iter},SMT)
end

function SW (iter)
    if callable(iter) then
		return setmetatable({iter=iter},SMT)
	else
		return iter
	end
end