initial files

Project.toml

+name = "Periods"
+uuid = "0c1d1a06-9168-427d-90e3-b4d73349562f"
+authors = ["michel "]
+version = "0.1.0"

src/Periods.jl

+module Periods
+
+include("SimplePeriods.jl")
+
+end # module

src/SimplePeriods.jl

+@enum Frequency Year Semester Quarter Month Week Business Day
+
+struct SimplePeriod
+    ordinal::Int64
+    frequency::Frequency
+end
+
+function SimplePeriod(year, subperiod, frequency)
+    if frequency == Year
+        ordinal = year - 1970
+    elseif frequency == Semester
+        @assert(subperiod in 1:2)
+        ordinal = 2*(year - 1970) + subperiod - 1
+    elseif frequency == Quarter
+        @assert(subperiod in 1:4)
+        ordinal = 4*(year - 1970) + subperiod - 1
+    elseif frequency == Month
+        @assert(subperiod in 1:12)
+        ordinal = 12*(year - 1970) + subperiod - 1
+    elseif frequency == Week
+        ordinal = week1970(year, week)
+    end
+end