# Where is the lowering of end within \[ \] documented
**URL:** https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736
**Category:** General Usage
**Tags:** question, indexing, lowering
**Created:** [April 16, 2026, 10:42am UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736 "2026-04-16T10:42:22Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [April 16, 2026, 10:42am UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/1 "2026-04-16T10:42:22Z")
Where is the lowering of `end` within `[]` _documented_? Ie the fact that it is assigned a value from `lastindex`, as in
```julia
julia> Meta.@lower (1:4)[min(end, 5)]
:($(Expr(:thunk, CodeInfo(
1 ─ %1 = Main.:(:)
│ %2 = dynamic (%1)(1, 4)
│ %3 = Main.min
│ %4 = dynamic Base.lastindex(%2)
│ %5 = dynamic (%3)(%4, 5)
│ %6 = dynamic Base.getindex(%2, %5)
└── return %6
))))
```
I just realized that I know this, but can’t find it in the docs (context: someone asked me about it and I wanted to share a docs section that explains it.)
---
### Author:  [@technocrat](https://discourse.julialang.org/u/technocrat)
#### Post date: [April 16, 2026, 10:54am UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/2 "2026-04-16T10:54:47Z")
I think it’s hidden away in the compiler internals.
---
### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [April 16, 2026, 11:13am UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/3 "2026-04-16T11:13:29Z")
It’s documented in the `lastindex` docstring, which says:
> The syntaxes `A[end]` and `A[end, end]` lower to `A[lastindex(A)]` and `A[lastindex(A, 1), lastindex(A, 2)]`, respectively.
The `end` docstring also says:
> `end` may also be used when indexing to represent the last index of a collection or the last index of a dimension of an array.
but it should probably cross-reference `lastindex` specifically.
Probably it should also be referenced from the “Arrays” chapter of the manual, which currently only says:
> As a special part of this syntax, the `end` keyword may be used to represent the last index of each dimension within the indexing brackets, as determined by the size of the innermost array being indexed.
>
>
> The fact that \`end\` in brackets lowers to a \`lastindex\` call was documented in t…he \`lastindex\` docstring, but was only alluded to more vaguely as the "last index" in other places, e.g. in the Arrays chapter of the manual or the \`end\` docstring. Similarly for \`begin\` and \`firstindex\`.
>
> (Inspired by a \[discourse thread\](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736?u=stevengj).)
---
### Author:  [@foobar\_lv2](https://discourse.julialang.org/u/foobar_lv2)
#### Post date: [April 16, 2026, 12:17pm UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/5 "2026-04-16T12:17:41Z")
Funnily enough, this is done in the parser, not in lowering.
```julia-auto
julia> Meta.parse("[1][begin : end]")
:(([1])[var"begin":var"end"])
julia> Meta.parse("[begin : end]")
:([begin
#= none:1 =#
:
end])
julia> [begin : end]
1-element Vector{Colon}:
(::Colon) (generic function with 16 methods)
```
If you think about it for a second, then it is clear why this has to work that way: Macros.
That is quite the footgun for code generation!
And the distinction is not “internals”, it is public API (macros). So I guess the docs should say `var"begin"` and `var"end"` get lowered to appropriate firstindex/lastindex called when within an indexing bracket; and `begin`/`end` sometimes get parsed into `var"begin"`/`var"end"` when within an indexing bracket.
…and the “sometimes” is really non-trivial – see `begin : end`, which plausibly could have been `getindex(A, Colon())` or `getindex(A, Colon()(firstindex(A), lastindex(A)))`. Luckily both give the same result for most (all?) Base types.
---
### Author:  [@mbauman](https://discourse.julialang.org/u/mbauman)
#### Post date: [April 16, 2026, 1:56pm UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/7 "2026-04-16T13:56:50Z")
It’s also documented on the `end` keyword itself!
```julia-auto
help?> end
search: end tand read secd sind nand rand bind
end
end marks the conclusion of a block of expressions, for example module,
struct, mutable struct, begin, let, for etc.
end may also be used when indexing to represent the last index of a
collection or the last index of a dimension of an array.
Examples
≡≡≡≡≡≡≡≡
julia> A = [1 2; 3 4]
2×2 Matrix{Int64}:
1 2
3 4
julia> A[end, :]
2-element Vector{Int64}:
3
4
```
---
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [April 16, 2026, 2:11pm UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/8 "2026-04-16T14:11:09Z")
> [@mbauman](#):
>
> It’s also documented on the `end` keyword itself!
Yes, this is understood, but _what_ this feature does precisely is not documented there.
Some languages have similar keywords or concepts, but do not implement them in such a general way.
---
### Author:  [@photor](https://discourse.julialang.org/u/photor)
#### Post date: [April 18, 2026, 1:38am UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/9 "2026-04-18T01:38:24Z")
So I don’t think it is a good way to index the first and last elements. Mathematica’s 1 and -1 are quite concise, as long as you give up offset arrays.
---
### Author:  [@Sevi](https://discourse.julialang.org/u/Sevi)
#### Post date: [April 18, 2026, 9:23am UTC](https://discourse.julialang.org/t/where-is-the-lowering-of-end-within-documented/136736/10 "2026-04-18T09:23:33Z")
> [@foobar\_lv2](#):
>
> ```julia-repl
> julia> Meta.parse("[1][begin : end]")
> :(([1])[var"begin":var"end"])
>
> ```
Does this behavior depend on the Julia version or so? If I try this in 1.12.6 (and 1.10.11), it looks like this:
```julia-repl
julia> Meta.parse("[1][begin : end]")
:(([1])[begin:end])
```
`var"begin"` and `var"end"` don’t seem to exist for me.
PS: Or did you define them by hand to make a point? I’m not sure why anyone would do that though 😅 And even if I set `var"begin"` and `var"end"` to something, the above still parses to the same for me (no `var"begin"` just `begin`).