Sigils

Sigils in Elixir are a mechanism for working with textual representations using a compact and specialized syntax. They provide a convenient way to create and manipulate different types of data.

Syntax

~<letter><delimiter><content><delimiter><modifiers>

common <delimiter> are ", ', (, [, {, <, /, but you are free to use other chars.

Built-in Sigils

String: `~s` and `~S`

one reason to use ~s is that it's easier to include double quotes:

~s(double "quotes")
# "double \"quotes\""

uppercased sigils like ~S ignores interpolation or escaping

~S(\n #{})
# "\\n \#{}"

Character List: `~c` and `~C`

hd(~c"a")
# 97

Regular Expression: `~r` and `~R`

"a" =~ ~r/^[a-z]$/
# true

Word List: `~w` and `~W`

~w(split by space)
# ["split", "by", "space"]

~w(a for atom)a
# [:a, :for, :atom]

Date/Time Sigils: `~D`, `~T`, `~U`, `~N`

~D[1970-01-01]
# ~D[1970-01-01]

Custom Sigils

defmodule HTMLSigil do
  def sigil_h(string, _opts) do
    string
    |> String.replace("&", "&amp;")
    |> String.replace("<", "&lt;")
    |> String.replace(">", "&gt;")
  end
end

import HTMLSigil
html = ~h(<div>Hello & welcome</div>)
# "&lt;div&gt;Hello &amp; welcome&lt;/div&gt;"

Phoenix