IEx introduction

iex allows us to type our code line-by-line, and executes it one line at a time. Typing iex in your terminal / command prompt will open an interactive elixir shell. Here are some of its features:

• Autocomplete: To discover what functions and modules are available, type anything and press tab to get a list of suggestions.
• History: You can use the up and down arrow keys to browse through the history of commands.
• Expressions: You can type an expression and hit enter to evaluate it and get its result.

iex also provides some helper functions to make our lives easier. Just type h and press enter to get a list of all the helper functions. Here’s a few of them:

• Standard shell-like functions: These include functions like cd, clear, ls, pwd, etc. If you’ve ever used a unix-like shell, you know what they do.
• Code compilation / information related functions:
  • c (compile)
  • h (help)
  • i (info about last value or given term)
  • recompile (the entire project) / r (to recompile a single module)
  • t (print types for a given module or function)
  • runtime_info (get info about the current system and runtime)
  • v (return the value of the nth expression in history, or the last expression by default. Can be negative)

🔥 WARNING: Code is evaluated line-by-line in iex and not compiled. This means that any benchmarking done in the shell is going to have skewed results, since compilers can optimize the code they’re building, but an interpreter like iex can’t do the same. TL;DR: don’t run any profiling or benchmarks in the shell, the results won’t show the true picture.

Examples

iex> 1 + 2
3
iex> 3 * 4
12
iex> v(-1)
12
iex> v(1)
3
iex> i
Term
  3
Data type
  Integer
Reference modules
  Integer
Implemented protocols
  IEx.Info, Inspect, List.Chars, String.Chars
iex>