a=rand(10_000_000)
b=rand(10_000_000)

a*b                 # ❌
a.*b
sin(a)              # ❌
sin.(a)             # Broadcasting
[sin(i) for i in a] # Comprehension

# Broadcasting is faster – no need to
# allocate intermediate memory
@time sin.(a) .+ cos.(b);
@time [sin(i) for i in a] .+ [cos(i) for i in b];

# In-place assignment (no memory allocation)
c = zeros(size(a))
@time c .= sin.(a).^2 .+ cos.(b).^2;
# Tired of writing dots?
@. c = sin(a)^2 + cos(b)^2

1//3
typeof(ans)    # ans = result of previous line
typeof(Int8(1)//Int8(3))
typeof([1,2,3])
typeof([1 2 3])
typeof(Int8[1,2,3])
typeof([1 2;3 4.1])

Integer <: Number
Int8 <: Integer
Int8 <: Number
Float32 <: Number
Float32 <: Integer

mutable struct MyType
    id::Int64
    text::String
end

x = MyType(10, "Hello")

# Define addition of our type
Base.:+(a::MyType, b::MyType) = MyType(a.id + b.id, "Sum")
x + MyType(1, "xxx")

x->x^2
ans(5)  # call

a=rand(10)
# Return elements > 0.5
filter(x->x>0.5, a)
[x for x in a if x > 0.5]
a[a .> 0.5]

fun(x::Number) = "Number "*string(x)
methods(fun)
fun(1)
fun(1.1)
fun("1.1")
fun(x::String) = "String "*x
methods(fun)
fun("1.1")

# Functions can have many methods
methods(+)
methods(show)

@doc atan
typeof(@doc atan)
show(stdout, MIME("text/plain"), @doc atan)
show(stdout, MIME("text/html"), @doc atan)

@time rand(Int(1e6));

using BenchmarkTools
@benchmark rand(Int(1e6))

@code_native sum(1:5)

a = [1, 2, 3]
# Don’t perform bounds checking
@inbounds a[2]

using Measurements
a = 5.2 ± 1.0
typeof(a)
b = 3.7 ± 1.0
a + b
a * b
a / b

using Unitful
using Unitful.DefaultSymbols
using Unitful: hr

1m + 3cm |> cm |> float
sin(90)
sin(90°)
sin(π/2)

15m/3s

10km/hr |> m/s
10km/hr |> m/s |> float
0°C |> K |> float

pwd()
# Switch to package manager
]
?
# create a new project or activate existing
activate .
add Pipe
;cat Project.toml
cat Manifest.toml

using IJulia
notebook()

import Pluto
Pluto.run()

ls -l /nix/store | head
ls -lh $(which bash)
tree $(dirname $(readlink $(which bash)))/.. | head

ls -l /nix/var/nix/profiles/per-user/$USER

nix-env --rollback
nix-env --list-generations
nix-env --switch-generation 43

nix-build '<nixpkgs>' -A gnuplot
git clone https://github.com/NixOS/nixpkgs/
nix-build ./nixpkgs -A gnuplot
edit ./nixpkgs/pkgs/tools/graphics/gnuplot/default.nix
nix-build ./nixpkgs -A gnuplot
ls -l result
nix log result/  # show build log
nix log /nix/store/mr9l6qjimaarcak7s5rk6j1h4b16rpw9-gnuplot-5.4.3
# See the log from “distro” build
nix log $(dirname $(readlink $(which bash)))/..
cd nixpkgs
# Rebuild all packages depending on
nixpkgs-review wip

mc --version
echo $PATH
echo $PATH | tr : \\n
nix-shell -p mc
mc --version
echo $PATH | tr : \\n
exit
nix-shell --pure -p mc  # only explicitly mentioned dependencies are available
echo $PATH | tr : \\n
exit

nix-shell -p mc -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/d1c3fea7ecbed758168787fe4e4a3157e52bc808.tar.gz

git clone https://github.com/wentasah/boardproxy
cd boardproxy
make  # fails due to missing dependencies
nix-shell  # make deps from shell.nix or default.nix available
make  # success

nix-build docker-image.nix
docker load < result
docker run -it gnuplot:nmg0lnkf1dl7a0bsv152a6xphkxm9sq9

mkdir tmp && cd tmp
tar xf ../result
ls -lR
tar tf */layer.tar

{ pkgs ? import <nixpkgs> {}
, boardproxy ? import ./boardproxy/default.nix { inherit pkgs; }
}:

pkgs.dockerTools.buildImage {
  name = "boardproxy";
  config = {
    Entrypoint = "${boardproxy}/bin/boardproxy";
  };
}

nix-build docker-boardproxy.nix
docker load < result
docker run -it boardproxy:60j25jpwggspx1mg694143ddchsynq1q --help

{ pkgs ? import <nixpkgs> {}
}:
pkgs.redis.overrideAttrs (old: {
  # no need for systemd support in our docker image
  makeFlags = old.makeFlags ++ ["USE_SYSTEMD=no"];
  # build static binary with musl
  preBuild = ''
     makeFlagsArray=(PREFIX="$out"
                     CC="${pkgs.musl.dev}/bin/musl-gcc -static"
                      CFLAGS="-I${pkgs.musl.dev}/include"
                      LDFLAGS="-L${pkgs.musl.dev}/lib")
    '';
  # Let's remove some binaries which we don't need
  postInstall = "rm -f $out/bin/redis-{benchmark,check-*,cli}";
})