Building Blocks

Elixir in Action: Chapter 2

The nitty gritty of getting started:

  • IEx
  • Variables
  • Code Organization
  • Data types
  • Operators, and
  • Runtime

I finally clicked on the use of & in lambdas. The syntax always looked foreign to me. The following are equivalent:

lambda = fn a, b, x -> a + b - c
lambda = &(&1 + &2 - &3)

Notable Notes and Quotes

  • When composing a multi-line expression in IEx, typing #iex:break on a line breaks out to the base prompt.
  • Add the application or library name to the start of module names to ensure they are distinct across modules/projects.
  • “A function must always be a part of a module.”
  • “Because arity distinguishes multiple functions of the same name, it’s not possible to have a function accept a variable number of arguments”
  • The only booleans are :true and :false (syntactic sugar true and false).
  • nil and false are falsy values, everything else is truthy.
  • Lists are linked lists, not arrays. Accessing an element requires traversing the links.
  • Enum.each iterates without producing a new value. Example is typically IO.puts. To change value, use Enum.map.
  • “A closure always captures a specific memory location. Rebinding a variable doesn’t affect the previously defined lambda that references the same symbolic name”
  • Use apply to dynamically call functions.

Quotes are excerpts From Elixir in Action, Third Edition, Sasa Juric. All notes and comments are my own opinion. Follow me at @rgacote@genserver.social

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