A Mad Dash Through Elixir Types

Notes

1. ?≠ returns a codepoint: 8800.

2. Dividing two integers returns a float. Use div and trunc to get integer results.

3. In Elixir, nil is false.

4. Regular expressions are based on PCRE (Perl lives on!).

5. =~ performs a regular expression match

   iex> str = "once upon a time"
   iex> str =~ ~r/u..n/
   true

6. =~ also accepts a string as its right hand argument, in which case it returns true if the left string contains the right.

7. Lists are not arrays. You cannot calculate an offset to a specific element.

8. map[:missingKey] returns nil. map.missingKey raises an exception.

Exercises

Strings

• Interpolate current date/time using double-quoted string and a sigil.

  iex> now = Time.utc_now
  
  iex> "The time is approximately #{now.hour}:#{now.minute} UTC."
  "The time is approximately 13:34 UTC."
  
  iex> ~s/The time is approximately #{now.hour}:#{now.minute} UTC./
  "The time is approximately 13:34 UTC."

• Use IO.puts to output: 1 + 2 = #{ 1 + 2 }

  iex> IO.puts(~S"1 + 2 = #{ 1 + 2 }")
  1 + 2 = #{ 1 + 2 }
  :ok

• Convert string into a list of words.

  iex> ~w/now is the time/
  ["now", "is", "the", "time"]

Regular Expressions

• Return true if string contains an a, followed by any single character, followed by a c.

  iex> str =~ ~r/a.c/
  true

• Replace every occurrence of cat with dog`.

  iex>  Regex.replace(~r/cat/, "double cat cats", "dog")
  "double dog dogs"

• Replace only the first occurrence:

  iex>  Regex.replace(~r/cat/, "double cat cats", "dog", global: false)
  "double dog cats"

All notes and comments are my own opinion. Follow me at @rgacote@genserver.social