mra-worksheet.rb

# MRA - Multidimensional Relational Algebra

1 + 2  # => 3
-1     # => -1

s = [1, 2, 3]
t = [4, 5, 6]

-s      # => [-1, -2, -3]
s + 3   # => [4, 5, 6]

s + t   # => [5, 6, 7, 6, 7, 8, 7, 8, 9]

s = [1, 2, 3]
s1 = -s        # => [-1, -2, -3]
s2 = s + 3     # => [ 4,  5,  6]

s1 + s2        # => [3, 3, 3]
# autojoin!!!

s = [(0, 1), (1, 2), (2, 3)]
s1 = -s = [(0, -1), (1, -2), (2, -3)]
s2 = s + 3 = [(0, 4), (1, 5), (2, 6)]

s1 + s2 = [(0, 3), (1, 3), (2, 3)]

s + count(*)

# scalars are implicitly singleton sets

42   # => [42]

s = [([0], 1), ([1], 2), ([2], 3)]
s1 = -s = [([0], -1), ([1], -2), ([2], -3)]
s2 = s + 3 = [([0], 4), ([1], 5), ([2], 6)]

s1 + s2 = [([0], 3), ([1], 3), ([2], 3)]


42   # => [([], 42)]

s + 42           # => [([0], 43), ([1], 44), ([2], 45)]
s + count(*)     # => [([0], 43), ([1], 44), ([2], 45)]

s = [([0], 1), ([1], 2), ([2], 3)]                              # /datasource/s3/s.json
t = [([100], 50), ([101], 60), ([102], 70), ([103], 80)]        # /datasource/s3/t.json

st = s + t = [        # select s + t from s join t
  ([(0 && 100)], 51), ([(1 && 100)], 52), ([(2 && 100)], 53),
  ([(0 && 101)], 61), ([(1 && 102)], 62), ([(2 && 101)], 63),
  # ...
  # ...
]

st * (t + 1) = [  # select (s + t) * (t + 1) from s join t
  ([(0 && 100)], 102), ([(1 && 100)], 103), ([(2 && 100)], 104),
  ([(0 && 101)], 111), ([(1 && 102)], 112), ([(2 && 101)], 63),

]


# :meta: clearscopes!

s = [([0], {:a => true, :b => nil}), ([1], {:a => false, :b => "hi"}), ([2], {:a => true, :b => 42})]

s[*] = [
  ([0, :a], true),
  ([0, :b], nil),
  ([1, :a], false),
  ([1, :b], "hi"),
  ([2, :a], true),
  ([2, :b], 42)
]

s[*] + 42 + [
  ([2, :b], 84)
]

s.b = [([0], nil), ([1], "hi"), ([2], 42)]

s[*] + s.b = [
  ([1, :b], "hihi"),
  ([2, :b], 84)
]


count(*)
sum(*)
average(*)


nums = [([0], 1), ([1], 2), ([2], 3)]   # /datasource/s3/nums.json

sum(nums)           # => [([], 6)]
nums + sum(nums)    # => [([0], 7), ([1], 8), ([2], 9)]

count(s[*]) = [
  ([0], 2),
  ([1], 2),
  ([2], 2)
]

count(count(s[*])) = [([], 3)]

unshift_array(nums) = [([], [1, 2, 3])]

unshift_array(s[*]) = [
  ([0], [true, nil]),
  ([1], [false, "hi"]),
  ([2], [true, 42])
]

s = [([0], {:a => true, :b => nil}), ([1], {:a => false, :b => "hi"}), ([2], {:a => true, :b => 42})]

sgrouped = s.group_by { |row| row.a } = [
  ([true, 0], {:a => true, :b => nil}),
  ([false, 1], {:a => false, :b => "hi"}),
  ([true, 2], {:a => true, :b => 42})
]

count(sgrouped) = [
  ([false], 1),
  ([true], 2)
]