# The 'do'-keyword when it doesn't create an anonymous function and pass it as the first argument to a function call
**URL:** https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471
**Category:** New to Julia
**Created:** [February 11, 2023, 2:52pm UTC](https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471 "2023-02-11T14:52:40Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@kingoslo](https://discourse.julialang.org/u/kingoslo)
#### Post date: [February 11, 2023, 2:52pm UTC](https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471/1 "2023-02-11T14:52:40Z")
Hello there,
I am trying to learn Julia, and I came by the do keyword in a setting that I do not understand. So I am asking for some help to work out what happens here.
```julia
HDF5.h5open(fname, "r") do fd
#=
lots of stuff involving fd
=#
end
```
I can see here that the [do keyword makes an anonymous function](https://docs.julialang.org/en/v1/base/base/#do) and pass it as the first argument to the function on the left hand side of the do keyword. But the documentation says that the [HDF5.h5open](https://juliaio.github.io/HDF5.jl/stable/#Opening-and-closing-files) function accepts exactly two arguments, and neither should be a function. So in this case the `do`-keyword must have some other meaning.
Could you please explain?
Kind regards
---
### Author:  [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)
#### Post date: [February 11, 2023, 3:00pm UTC](https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471/2 "2023-02-11T15:00:58Z")
It seems more likely that the `h5open` documentation is incomplete than the `do` keyword does something undocumented. Based on how the standard `open` function works, I would expect the above to effectively do
```julia
fd = HDF5.h5open(fname, "r")
#=
lots of stuff involving fd
=#
close(fd)
```
with the twist that the final `close(fd)` is run also when `lots of stuff involving fd` is interrupted by an error.
---
### Author:  [@jling](https://discourse.julialang.org/u/jling)
#### Post date: [February 11, 2023, 3:09pm UTC](https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471/3 "2023-02-11T15:09:07Z")
>
---
### Author:  [@HugoTrentesaux](https://discourse.julialang.org/u/HugoTrentesaux)
#### Post date: [October 29, 2024, 9:49pm UTC](https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471/4 "2024-10-29T21:49:44Z")
> [@kingoslo](#):
>
> the do keyword in a setting that I do not understand.
“do” comes from julia itself:
```julia
help?> do
search: do Docs download DomainError @doc Cdouble stdout @ __dot__ ReadOnlyMemoryError pseudos fieldoffset isreadonly dropdims istaskdone fdio
do
Create an anonymous function and pass it as the first argument to a function call. For example:
map(1:10) do x
2x
end
is equivalent to map(x->2x, 1:10).
Use multiple arguments like so:
map(1:10, 11:20) do x, y
x + y
end
```
When you are unsure about something in julia, do not hesitate to use the help by entering `?` in a julia REPL.
---
### Author:  [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)
#### Post date: [October 29, 2024, 9:54pm UTC](https://discourse.julialang.org/t/the-do-keyword-when-it-doesnt-create-an-anonymous-function-and-pass-it-as-the-first-argument-to-a-function-call/94471/5 "2024-10-29T21:54:59Z")
I would prefer if you don’t quote me partially to completely change the meaning of what I wrote.