Factory function unable to return the local iterator to for loop in lua? -

why can't factory function fromto return local function iter iterator loop?

function fromto(from,to)     return iter,to,from-1 end  local function iter(to,from)--parameter:invariant state, control variable     = + 1     if <=         return     else         return nil     end end  in fromto(1,10)     print(i) end 

as @yuhao says, scheme can work. there few ways rearrange code. here's one:

local function fromto(from,to)     --parameter:invariant state, control variable     local function iter(to,from)         = + 1         if <=             return         else             return nil         end     end      return iter,to,from-1 end   in fromto(1,10)     print(i) end 

two things understand: variable scope , functions values.

1. variables either global or local. local variables lexically scoped. in scope statement following declaration end of block. if name not name of local variable becomes global variable reference. on line 2, iter global variable.

2. functions not declared, values created when function definition expression executed. (a function defintion statement alternate syntax function definition expression , assignment variable.) also, functions don't have names. referenced 1 or more variables. so, function value exist , referenced iter variable until execution control passes through lines contain function definition. in code, that's end of line 11.