Advent of code 2016 by @schovi

• from Advent of code 2016
• using and learning Crystal language

Run

crystal run ./1/solution.cr

Notes for Crystal

Day 1

• There is no .to_sym on String, because symbols are converted into numbers during compile time.

• cant use return keyword in toplevel

some_array.map do |value|
  return 1
end

=>
in 1/some.cr:2: can't return from top level

• destructuring tuple in block is like ... do |(x,y)| ... end
  • but on toplevel x,y = tuple (which makes sense :)

### Day 2

• Watch your chars - Always confuse me if I have char or string!

### Day 3

Watch your maybe values in arrays

array = [1, 2, 3, 4]
typeof(array.in_groups_of(2))    # => Array(Array(Int32 | Nul))
typeof(array.in_groups_of(2, 0)) # => Array(Array(Int32)) 

### Day 4

• Again nil values! But can be handle with not_nil!

matcher = /([a-z\-]+)\-(\d+)\[([a-z]+)\]/
matcher.match(some_string).not_nil!

• map(&.[0].strip.capitalize[0..2]) is fucking awesome! Go to trash to_proc in ruby.

Day 5

• Fist "computing heavy" quest. Tried some benchark. Never forget about --release flag :D

• Tried naive version with channels (concurrency). Without batching it blow my computer up :)