Kernel.-exclamation-mark

You're seeing just the macro -exclamation-mark, go back to Kernel module for more information.

Boolean "not" operator.

Receives any value (not just booleans) and returns true if value is false or nil; returns false otherwise.

Not allowed in guard clauses.

Examples

iex> !Enum.empty?([])
false

iex> !List.first([])
true