samples/iyi/grid.iyi

# The first program with a table in it - rows of cells, built from their
# coordinates, read across, down and along the diagonal.
#
#   ./bin/iyi run samples/iyi/grid.iyi
#
# An array built by a block, a range asked for a value per position, and
# the small set a list of numbers gets asked for: reversed, unique, paired
# with another, one taken out. Like `basics`, `inventory` and `config`, this
# documents no rule; it is here because the prelude grows only when a
# program in this repository needs something (SPEC.md 0.1.0 item 3).
module samples/grid

n = 4
grid = Array(Array(Int32)).new(n) { |r| Array(Int32).new(n) { |c| r * n + c } }
grid.each { |row| puts row.map { |v| v.to_s.rjust(3) }.join }
# => 0  1  2  3
# => 4  5  6  7
# => 8  9 10 11
# => 12 13 14 15

puts grid.map(&.sum).sum                                 # => 120
puts (0...n).map { |i| grid[i][i] }                      # => [0, 5, 10, 15]
puts (0...n).map { |c| grid.map { |row| row[c] } }.first # => [0, 4, 8, 12]

# 2. A list of numbers, asked the usual things.
puts (1..5).to_a.reversed           # => [5, 4, 3, 2, 1]
puts (1..10).select { |i| i.even? } # => [2, 4, 6, 8, 10]
puts (1..10).sum                    # => 55
puts [3, 1, 3, 2, 1].uniq           # => [3, 1, 2]
puts [1, 2, 3].zip(["a", "b", "c"]) # => [{1, "a"}, {2, "b"}, {3, "c"}]

letters = ["b", "a", "c"]
puts letters.index("c").inspect # => 2
puts letters.delete("a")        # => a
puts letters                    # => ["b", "c"]

# 3. A line built piece by piece, then ended.
5.times { |i| print i }
puts # => 01234