# Code availability: user-input functions

**URL:** https://discourse.julialang.org/t/code-availability-user-input-functions/40213
**Category:** General Usage
**Created:** [May 26, 2020, 6:52pm UTC](https://discourse.julialang.org/t/code-availability-user-input-functions/40213 "2020-05-26T18:52:06Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Egwene\_al\_Vere](https://avatars.discourse-cdn.com/v4/letter/e/df788c/32.png) [@Egwene\_al\_Vere](https://discourse.julialang.org/u/Egwene_al_Vere)
#### Post date: [May 26, 2020, 6:52pm UTC](https://discourse.julialang.org/t/code-availability-user-input-functions/40213/1 "2020-05-26T18:52:06Z")

</div>

In an effort to make my main calculation code transparent to the parallelized implement, I want to have a user-defined function, then run it in parts of the calculations, doing all the setting up of parallelized calculation “invisible”. I understand I need to make the user-defined function available across cores. As a MWE:

`foo.jl`:

```julia
using Distributed

function p_call(func)
    ps = addprocs(2)
    r = pmap(x -> func(x), 1:4)
    rmprocs(ps)
    r
end

```

Use it as

```julia
include("foo.jl")

f(x) = x*im

println(p_call(f))

```

fails with

> ERROR: LoadError: On worker 2:  
> UndefVarError: #f not defined

sort of expected; however, if the above is wrapped inside another function:

```julia
include("foo.jl")
function run_code()
    f(x) = x*im
    p_call(f)
end

println(run_code())

```

without explicitly making `@everyhere f`, this script works. How to best understand this and what is the preferred way to take in a user-provided function f and use it in a parallelized calculation, without exposing the parallelize setup to the user code? Thanks!