# Type unstability with args
**URL:** https://discourse.julialang.org/t/type-unstability-with-args/123987
**Category:** New to Julia
**Created:** [December 19, 2024, 11:03am UTC](https://discourse.julialang.org/t/type-unstability-with-args/123987 "2024-12-19T11:03:55Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@hbrochet](https://discourse.julialang.org/u/hbrochet)
#### Post date: [December 19, 2024, 11:03am UTC](https://discourse.julialang.org/t/type-unstability-with-args/123987/1 "2024-12-19T11:03:55Z")
Hello,
I would like to make the following function type stable:
> function f(args…)
> t = Tuple([arg] for arg in args)
> return t
> end
>
> f(1,2.0,“s”)
a run from @code\_warntype gives me
> julia\> @code\_warntype f2(1,2.0,“s”)
> MethodInstance for f2(::Int64, ::Float64, ::String)
> from f2(args…) @ Main REPL[40]:1
> Arguments
> #self#::Core.Const(Main.f2)
> args::Tuple{Int64, Float64, String}
> Locals
> #25::var"#25#26"
> t::Tuple{Vararg{Vector}}
> Body::Tuple{Vararg{Vector}}
> 1 ─ %1 = Main.Tuple::Core.Const(Tuple)
> │ %2 = Main.:(var"#25#26")::Core.Const(var"#25#26")
> │ (#25 = %new(%2))
> │ %4 = #25::Core.Const(var"#25#26"())
> │ %5 = Base.Generator(%4, args)::Base.Generator{Tuple{Int64, Float64, String}, var"#25#26"}
> │ (t = (%1)(%5))
> │ %7 = t::Tuple{Vararg{Vector}}
> └── return %7
The type of args is inferred correctly. I thought it would be enough to guess the correct type of t but somehow there is a Vararg which pops up.
Any help would be appreciated.
---
### Author:  [@jakobnissen](https://discourse.julialang.org/u/jakobnissen)
#### Post date: [December 19, 2024, 11:42am UTC](https://discourse.julialang.org/t/type-unstability-with-args/123987/2 "2024-12-19T11:42:21Z")
The issue is that looping over the tuple results in the element type being inferred as `Any`. (that could possibly be changed, to be fair).
So, instead of using a for loop, you can access the tuple elements in a different manner. For example, here, I access them by indexing:
```julia
function f(args...)
ntuple(length(args)) do i
[args[i]]
end
end
```
This is type stable.
---
### Author:  [@hbrochet](https://discourse.julialang.org/u/hbrochet)
#### Post date: [December 19, 2024, 11:52am UTC](https://discourse.julialang.org/t/type-unstability-with-args/123987/3 "2024-12-19T11:52:13Z")
Thank you very much it works !
I was not aware of this method to create ntuple.
---
### Author:  [@cjdoris](https://discourse.julialang.org/u/cjdoris)
#### Post date: [December 19, 2024, 1:17pm UTC](https://discourse.julialang.org/t/type-unstability-with-args/123987/4 "2024-12-19T13:17:24Z")
`map` should be type stable too
```julia
map(args) do x
[x]
end
```