# What's your favorite syntactical sugar in Julia
**URL:** https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781
**Category:** Teaching & Outreach
**Tags:** question
**Created:** [November 8, 2020, 10:33am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781 "2020-11-08T10:33:13Z")
**Posts on this page:** 20
**Page:** 4
### Author:  [@Tim\_G](https://discourse.julialang.org/u/Tim_G)
#### Post date: [May 17, 2021, 3:20am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/61 "2021-05-17T03:20:38Z")
Primes.jl looks very suspicious. 🤔
`(primes(999).^2).% 24`
---
### Author:  [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)
#### Post date: [May 17, 2021, 4:49am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/62 "2021-05-17T04:49:58Z")
that’s correct, it is a fact for all primes \>= 5
Squared Primes Modulo 24
Roger B. Nelsen
Mathematics Magazine, 93 (2020) pg 228
DOI: 10.1080/0025570X.2020.1736877
---
### Author:  [@Wei\_Yang](https://discourse.julialang.org/u/Wei_Yang)
#### Post date: [May 17, 2021, 5:25am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/63 "2021-05-17T05:25:28Z")
Julia and Primes.jl turned many problems on [https://projecteuler.net/](https://projecteuler.net/) into jokes 😂
---
### Author:  [@xiaodai](https://discourse.julialang.org/u/xiaodai)
#### Post date: [May 19, 2021, 4:35am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/65 "2021-05-19T04:35:15Z")
Since Julia 1.6 I think
```julia
a = 1
b = 2
c = 3
d = 4
f(a, b; c, d) = a+b+c+d
f(a, b; c = c, d = d)
# no need to name them with `=` if variable name is same as argument name
f(a, b; c, d)
```
---
### Author:  [@viraltux](https://discourse.julialang.org/u/viraltux)
#### Post date: [May 19, 2021, 5:33am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/66 "2021-05-19T05:33:56Z")
That’s what I do with Emacs
---
### Author:  [@chelate](https://discourse.julialang.org/u/chelate)
#### Post date: [May 19, 2021, 6:50am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/67 "2021-05-19T06:50:18Z")
When reduction operators take generators:
`f(k) = sum(x^2 for x in 1:k)`
even better than math notation!
---
### Author:  [@xiaodai](https://discourse.julialang.org/u/xiaodai)
#### Post date: [June 18, 2021, 11:26pm UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/68 "2021-06-18T23:26:36Z")
> [@chelate](#):
>
> f(k) = sum(x^2 for x in 1:k)
seems much slower than
`f(k) = sum((1:k).^2)`
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [June 19, 2021, 5:45am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/69 "2021-06-19T05:45:51Z")
Unfortunately, this doesn’t work with `sum`, but if we define our own:
```julia
julia> function mysum(f, r)
s = zero(f(first(r)))
for i ∈ r
s += f(i)
end
s
end
mysum (generic function with 1 method)
julia> @btime mysum(abs2, 1:$(Ref(10))[])
1.585 ns (0 allocations: 0 bytes)
385
julia> @btime mysum(abs2, 1:$(Ref(100))[])
1.586 ns (0 allocations: 0 bytes)
338350
julia> @btime mysum(abs2, 1:$(Ref(1000))[])
1.588 ns (0 allocations: 0 bytes)
333833500
julia> @btime mysum(abs2, 1:$(Ref(10000))[])
1.586 ns (0 allocations: 0 bytes)
333383335000
```
LLVM can optimize away the loop, so performance is independent of `k`.
---
### Author:  [@gustaphe](https://discourse.julialang.org/u/gustaphe)
#### Post date: [June 19, 2021, 5:47am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/70 "2021-06-19T05:47:53Z")
How so?
```julia
using BenchmarkTools, BenchmarkPlots, StatsPlots
K = 10_000
bg = BenchmarkGroup()
bg[:a] = @benchmark sum((1:$K).^2)
bg[:b] = @benchmark sum(x^2 for x in 1:$K)
bg[:c] = @benchmark sum(x -> x^2, 1:$K)
plot(bg; yscale=:log10)
```
The generator method is clearly much faster (but not as fast as the two argument version).
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [June 19, 2021, 10:58am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/71 "2021-06-19T10:58:10Z")
> [@gustaphe](#):
>
> The generator method is clearly much faster
But still about 100x slower than `mysum` would be at that size.
---
### Author:  [@gustaphe](https://discourse.julialang.org/u/gustaphe)
#### Post date: [June 19, 2021, 12:12pm UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/72 "2021-06-19T12:12:39Z")
It is indeed a lot faster even than `sum(f, x)`. I wonder what it is about `sum` that can’t be optimized like `mysum` can.
---
### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [June 19, 2021, 1:04pm UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/73 "2021-06-19T13:04:13Z")
I think it’s probably harder to constant fold pairwise summation.
---
### Author:  [@gustaphe](https://discourse.julialang.org/u/gustaphe)
#### Post date: [June 19, 2021, 1:42pm UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/74 "2021-06-19T13:42:23Z")
What about `sum` is pairwise? I would expect `sum` to do more or less the same thing as `mysum`
---
### Author:  [@dpsanders](https://discourse.julialang.org/u/dpsanders)
#### Post date: [June 19, 2021, 2:03pm UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/75 "2021-06-19T14:03:09Z")
It’s a technique to increase floating-point accuracy : [Pairwise summation - Wikipedia](https://en.m.wikipedia.org/wiki/Pairwise_summation)
---
### Author:  [@HerAdri](https://discourse.julialang.org/u/HerAdri)
#### Post date: [June 20, 2021, 6:29am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/76 "2021-06-20T06:29:23Z")
> [@gustaphe](#):
>
> `BenchmarkPlots`
```julia
pkg> add BenchmarkPlots
Updating registry at `C:\Users\Hermesr\.julia\registries\General`
Updating git-repo `https://github.com/JuliaRegistries/General.git`
ERROR: The following package names could not be resolved:
* BenchmarkPlots (not found in project, manifest or registry)
```
---
### Author:  [@gustaphe](https://discourse.julialang.org/u/gustaphe)
#### Post date: [June 20, 2021, 6:36am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/77 "2021-06-20T06:36:09Z")
My bad, that’s an unmerged pr. You can clone it and add by directory if you want.
>
>
> Adds a recipe to visualize the timings of a \`Trial\` or a \`BenchmarkGroup\` of \`Tr…ial\`s using boxplots. Only pulls in \`RecipesBase.jl\` so should be fairly low impact (but I don't know how best to check that).
>
> \`\`\`julia
> using BenchmarkTools, Plots, StatsPlots
> ...
> result = run(benchmarkgroup)
> plot(result, outliers=false)
> \`\`\`
>
> !\[benchmarks\](https://user-images.githubusercontent.com/6677110/109364965-4a2cb600-7890-11eb-81b3-7decf7ba1c6f.png)
---
### Author:  [@RoyiAvital](https://discourse.julialang.org/u/RoyiAvital)
#### Post date: [February 4, 2022, 10:03am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/78 "2022-02-04T10:03:59Z")
Another nice thing to do with `end` was given by @giordano in [a Slack thread](https://julialang.slack.com/archives/C6FGJ8REC/p1643494232240059):
Alexander Palvin:
I wish it was also possible to store the indexing expression in a variable.
```julia
ix = min(i, end)
x[ix] # same effect as x[min(i, end)]
```
@giordano , Using the package [`EndpointRanges.jl`](https://github.com/JuliaArrays/EndpointRanges.jl) solved it using:
```julia
julia> using EndpointRanges
julia> using EndpointRanges: Endpoint, IndexFunction
julia> Base.min(x::Endpoint, y::Endpoint) = IndexFunction(r->Base.min(x(r), y(r)))
julia> Base.min(x::Endpoint, y::Number) = IndexFunction(r->Base.min(x(r), y))
julia> Base.min(x::Number, y::Endpoint) = IndexFunction(r->Base.min(x, y(r)))
julia> m = min(3, iend)
IndexFunction{var"#5#6"{Int64, EndpointRanges.IEnd}}(var"#5#6"{Int64, EndpointRanges.IEnd}(3, EndpointRanges.IEnd()))
julia> (1:10)[m]
3
julia> (1:2)[m]
2
```
---
### Author:  [@sijo](https://discourse.julialang.org/u/sijo)
#### Post date: [February 4, 2022, 10:38am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/79 "2022-02-04T10:38:44Z")
@RoyiAvital that’s more an example of missing sugar though… It’s nice that it can be implemented but it would be nice to have something like this in Base.
---
### Author:  [@rmsmsgood](https://discourse.julialang.org/u/rmsmsgood)
#### Post date: [February 4, 2022, 10:54am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/80 "2022-02-04T10:54:54Z")
`@times` it’s amazing
---
### Author:  [@gustaphe](https://discourse.julialang.org/u/gustaphe)
#### Post date: [February 4, 2022, 11:48am UTC](https://discourse.julialang.org/t/whats-your-favorite-syntactical-sugar-in-julia/49781/81 "2022-02-04T11:48:35Z")
What package is that from?
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