# Generated Tuples of Functions
**URL:** https://discourse.julialang.org/t/generated-tuples-of-functions/59499
**Category:** Performance
**Created:** [April 17, 2021, 8:51pm UTC](https://discourse.julialang.org/t/generated-tuples-of-functions/59499 "2021-04-17T20:51:07Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)
#### Post date: [April 17, 2021, 8:51pm UTC](https://discourse.julialang.org/t/generated-tuples-of-functions/59499/1 "2021-04-17T20:51:07Z")
Continuing the discussion from [Performance and allocation issue with arrays of functions (v1.5)](https://discourse.julialang.org/t/performance-and-allocation-issue-with-arrays-of-functions-v1-5/45013):
I want to modify the question I originally posed above, to the case that the collection of functions on which I wish to evaluate may, themselves, be generated. I am thinking of the following example:
```julia
@generated function compute_values(x₀, Δt, nΔt, f::Tuple{Vararg{<:Any,K}}) where {K}
quote
x = x₀;
f_vals = zeros($K, nΔt)
for n in 1:nΔt
x += 0.5 * Δt * x
Base.Cartesian.@nexprs $K k -> f_vals[k,n] = (f[k])(x);
end
return f_vals
end
end
x₀ = 1.0;
Δt = 0.5;
nΔt = 10^2;
f_tuple = (x->x.^p for p in 1:5)
compute_values(x₀, Δt, nΔt, f_tuple)
```
but this gives the error:
```julia
MethodError: no method matching compute_values(::Float64, ::Float64, ::Int64, ::Base.Generator{UnitRange{Int64}, var"#3#5"})
Closest candidates are:
compute_values(::Any, ::Any, ::Any, ::Tuple{Vararg{Any, K}}) where K at In[3]:1
Stacktrace:
[1] top-level scope
@ In[6]:1
[2] eval
@ ./boot.jl:360 [inlined]
[3] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base ./loading.jl:1094
```
Any recommendations on how to handle this?
---
### Author:  [@Vasily\_Pisarev](https://discourse.julialang.org/u/Vasily_Pisarev)
#### Post date: [April 18, 2021, 7:33pm UTC](https://discourse.julialang.org/t/generated-tuples-of-functions/59499/2 "2021-04-18T19:33:37Z")
In this case, it is simply that `(x->x.^p for p in 1:5)` is not a tuple.
Use
```julia
f_tuple = ntuple(p -> (x -> x.^p), 5)
```
or
```julia
f_tuple = Tuple(x->x.^p for p in 1:5)
```
---
### Author:  [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)
#### Post date: [April 19, 2021, 4:31pm UTC](https://discourse.julialang.org/t/generated-tuples-of-functions/59499/3 "2021-04-19T16:31:55Z")
Ok, so that helps with what i had wanted to do. Now here’s a slight wrinkle. I would like to have something like:
```julia
Tuple(x->x.^p for p in 1:5, x->sin.(x))
```
where I have a sequence of functions which are generated from a loop, and then one more function, which I need to specify, and they all need to be grouped together in a single Tuple at the end. Note that the above does not work.
---
### Author:  [@Vasily\_Pisarev](https://discourse.julialang.org/u/Vasily_Pisarev)
#### Post date: [April 20, 2021, 10:20pm UTC](https://discourse.julialang.org/t/generated-tuples-of-functions/59499/4 "2021-04-20T22:20:11Z")
In that case, you may use
```julia
((x->x.^p for p in 1:5)..., x->sin.(x))
```
There might also be variants which are type stable.