return {

map_ = (function(f) return function(a) return function() return f(a()) end end end),

pure_ = (function(a) return function() return a end end),

bind_ = (function(a) return function(f) return function() return f(a())() end end end),

run = (function(f) return f() end),

["while"] = (function(f) return function(a) return function() while f() do a() end end end end),

["for"] = (function(lo)

return function(hi) return function(f) return function() for i = lo, hi - 1 do f(i)() end end end end

end),

foreach = (function(as) return function(f) return function() for i = 1, #as do f(as[i])() end end end end),

new = (function(val) return function() return {value = val} end end),

read = (function(ref) return function() return ref.value end end),

modifyImpl = (function(f)

return function(ref)

return function()

local t = f(ref.value)

ref.value = t.state

return t.value

end

end

end),

write = (function(a)

return function(ref)

return function()

ref.value = a

return a

end

end

end)

}