julia pairs data structure

pairs_study.jl

a_tuple = (1, 2)
a_pair = 1 => 2
a_tuple != a_pair
# true
# The elements are stored in the fields first and second
a_pair.first
# 1
a_pair.second
# 1
typeof(a_pair)
# Pair{Int64, Int64}
# construct pair with 'Pair' keyword 
Pair(1, 32.1)
# They can also be accessed via iteration
p = "foo" => 7
for x in p
    println(x)
end
# foo
# 7
# but a Pair is treated as a single "scalar" for broadcasting operations
r = "Pat" => "Mat"
r2 = [r.first, r.second]
uppercase(r2)
# ERROR
uppercase.(r2)
# 2-element Vector{String}:
#  "PAT"
#  "MAT"
uppercase(r)
# ERROR