1 files changed, 88 insertions, 9 deletions
diff --git a/stdlib/source/lux/time/year.lux b/stdlib/source/lux/time/year.lux
index 0ba2025c6..43e2181ab 100644
--- a/stdlib/source/lux/time/year.lux
+++ b/stdlib/source/lux/time/year.lux
@@ -1,19 +1,57 @@
 (.module:
   [lux #*
+   [abstract
+    [monad (#+ do)]
+    [codec (#+ Codec)]
+    [equivalence (#+ Equivalence)]
+    [order (#+ Order)]]
+   [control
+    ["." try (#+ Try)]
+    ["." exception (#+ exception:)]
+    ["<>" parser
+     ["<t>" text (#+ Parser)]]]
    [data
+    ["." text ("#@." monoid)]
     [number
-     ["n" nat]
-     ["i" int]]]])
+     ["n" nat ("#@." decimal)]
+     ["i" int ("#@." decimal)]]]
+   [type
+    abstract]])
 
-(type: #export Year
-  Int)
+(def: (internal year)
+  (-> Int Int)
+  (if (i.< +0 year)
+    (inc year)
+    year))
+
+(def: (external year)
+  (-> Int Int)
+  (if (i.> +0 year)
+    year
+    (dec year)))
+
+(exception: #export there-is-no-year-0)
+
+(abstract: #export Year
+  Int
+
+  (def: #export (year value)
+    (-> Int (Try Year))
+    (case value
+      +0 (exception.throw ..there-is-no-year-0 [])
+      _ (#try.Success (:abstraction (..internal value)))))
+
+  (def: #export value
+    (-> Year Int)
+    (|>> :representation ..external))
+  )
 
 (def: #export days
   365)
 
 (def: #export epoch
   Year
-  +1970)
+  (try.assume (..year +1970)))
 
 (type: #export Period
   Nat)
@@ -35,9 +73,10 @@
 ## https://en.wikipedia.org/wiki/Leap_year#Algorithm
 (def: #export (leap? year)
   (-> Year Bit)
-  (and (..divisible? (.int ..leap) year)
-       (or (not (..divisible? (.int ..century) year))
-           (..divisible? (.int ..era) year))))
+  (let [year (|> year ..value ..internal)]
+    (and (..divisible? (.int ..leap) year)
+         (or (not (..divisible? (.int ..century) year))
+             (..divisible? (.int ..era) year)))))
 
 (def: (with-year-0-leap year days)
   (let [after-year-0? (i.> +0 year)]
@@ -47,7 +86,8 @@
 
 (def: #export (leaps year)
   (-> Year Int)
-  (let [limit (if (i.> +0 year)
+  (let [year (|> year ..value ..internal)
+        limit (if (i.> +0 year)
                 (dec year)
                 (inc year))]
     (`` (|> +0
@@ -59,3 +99,42 @@
                   [i.+ ..era]
                   ))
             (..with-year-0-leap year)))))
+
+(def: (encode year)
+  (-> Year Text)
+  (let [year (..value year)]
+    (if (i.< +0 year)
+      (i@encode year)
+      (n@encode (.nat year)))))
+
+(def: #export parser
+  (Parser Year)
+  (do {@ <>.monad}
+    [sign (<>.or (<t>.this "-") (wrap []))
+     digits (<t>.many <t>.decimal)
+     raw-year (<>.codec i.decimal (wrap (text@compose "+" digits)))]
+    (<>.lift (..year (case sign
+                       (#.Left _)  (i.* -1 raw-year)
+                       (#.Right _) raw-year)))))
+
+(structure: #export codec
+  {#.doc (doc "Based on ISO 8601."
+              "For example: 2017")}
+  (Codec Text Year)
+  
+  (def: encode ..encode)
+  (def: decode (<t>.run ..parser)))
+
+(structure: #export equivalence
+  (Equivalence Year)
+
+  (def: (= reference subject)
+    (i.= (..value reference) (..value subject))))
+
+(structure: #export order
+  (Order Year)
+
+  (def: &equivalence ..equivalence)
+
+  (def: (< reference subject)
+    (i.< (..value reference) (..value subject))))