# What is the difference between in scope and loaded
**URL:** https://discourse.julialang.org/t/what-is-the-difference-between-in-scope-and-loaded/7452
**Category:** General Usage
**Tags:** question
**Created:** [December 2, 2017, 7:23am UTC](https://discourse.julialang.org/t/what-is-the-difference-between-in-scope-and-loaded/7452 "2017-12-02T07:23:48Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Chong\_Wang](https://discourse.julialang.org/u/Chong_Wang)
#### Post date: [December 2, 2017, 7:23am UTC](https://discourse.julialang.org/t/what-is-the-difference-between-in-scope-and-loaded/7452/1 "2017-12-02T07:23:48Z")
In the docs of parallel computing ([https://docs.julialang.org/en/stable/manual/parallel-computing/#Code-Availability-and-Loading-Packages-1](https://docs.julialang.org/en/stable/manual/parallel-computing/#Code-Availability-and-Loading-Packages-1)), there’s a sentence
`using DummyModule` causes the module to be loaded on all processes; however, the module is brought into scope only on the one executing the statement.
I do not understand this sentence. What is the difference between in scope and loaded?
---
### Author:  [@mauro3](https://discourse.julialang.org/u/mauro3)
#### Post date: [December 2, 2017, 3:15pm UTC](https://discourse.julialang.org/t/what-is-the-difference-between-in-scope-and-loaded/7452/2 "2017-12-02T15:15:53Z")
I think this is meant:
```julia
julia> using Compat
julia> @compat 1
1
julia> Compat.@compat 1
1
julia> @everywhere Compat.@compat 1
julia> @everywhere @compat 1
ERROR: On worker 2:
UndefVarError: @compat not defined
eval at ./boot.jl:235
eval_ew_expr at ./distributed/macros.jl:116
#106 at ./distributed/process_messages.jl:268 [inlined]
run_work_thunk at ./distributed/process_messages.jl:56
macro expansion at ./distributed/process_messages.jl:268 [inlined]
#105 at ./event.jl:73
#remotecall_fetch#141(::Array{Any,1}, ::Function, ::Function, ::Base.Distributed.Worker, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:354
remotecall_fetch(::Function, ::Base.Distributed.Worker, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:346
#remotecall_fetch#144(::Array{Any,1}, ::Function, ::Function, ::Int64, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:367
remotecall_fetch(::Function, ::Int64, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:367
(::##7#9)() at ./distributed/macros.jl:102
...and 1 more exception(s).
Stacktrace:
[1] sync_end() at ./task.jl:287
[2] macro expansion at ./distributed/macros.jl:112 [inlined]
[3] anonymous at ./:?
```
i.e. `using Compat` also executes `import Compat` on all nodes, but not `using Compat`. Whether this is good is disputed: [https://github.com/JuliaLang/julia/issues/9245](https://github.com/JuliaLang/julia/issues/9245)
---
### Author:  [@Chong\_Wang](https://discourse.julialang.org/u/Chong_Wang)
#### Post date: [December 3, 2017, 2:33am UTC](https://discourse.julialang.org/t/what-is-the-difference-between-in-scope-and-loaded/7452/3 "2017-12-03T02:33:58Z")
But this is working:
```julia
# Para.jl
module Para
export myidentity
function myidentity(x)
return x
end
end
```
```julia
# mytest.jl
push!(LOAD_PATH, "D:\\Working\\temp") # This is my path
using Para
# I expect an UndefVarError here,
# using @everywhere does raise an UndefVarError here though.
println(pmap(myidentity, ['a', 'b', 'c']))
```
Executing `julia -p 3 mytest.jl` in the commandline correctly yields `['a', 'b', 'c']`.
---
### Author:  [@mauro3](https://discourse.julialang.org/u/mauro3)
#### Post date: [December 3, 2017, 5:41am UTC](https://discourse.julialang.org/t/what-is-the-difference-between-in-scope-and-loaded/7452/4 "2017-12-03T05:41:17Z")
Yep, this is a bit odd. In particular the docs says:
```julia
help?> pmap
search: pmap TypeMapLevel TypeMapEntry promote_shape repmat typemax SparseMatrixCSC polygamma AbstractSparseMatrix PermutedDimsArray
pmap([::AbstractWorkerPool], f, c...; distributed=true, batch_size=1, on_error=nothing, retry_delays=[]), retry_check=nothing) -> collection
...
Note that f must be made available to all worker processes; see Code Availability and Loading Packages for details.
...
```