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1 {-# LANGUAGE DeriveDataTypeable #-}
2 {-# LANGUAGE FlexibleInstances #-}
3 {-# LANGUAGE TypeSynonymInstances #-}
4 {-# LANGUAGE OverloadedStrings #-}
5 {-# OPTIONS_GHC -fno-warn-orphans #-}
6 module Hcompta.Model.Amount where
7
8 import Data.Data
9 import qualified Data.List
10 import qualified Data.Map.Strict as Data.Map
11 import qualified Data.Foldable
12 import Data.Typeable ()
13
14 import qualified Hcompta.Calc.Balance as Calc.Balance
15 import qualified Hcompta.Model.Amount.Quantity as Quantity
16 import qualified Hcompta.Model.Amount.Style as Style
17 import qualified Hcompta.Model.Amount.Unit as Unit
18
19 -- * Type synonyms to submodules
20
21 type Quantity = Quantity.Quantity
22 type Style = Style.Style
23 type Unit = Unit.Unit
24
25 -- * The 'Amount' type
26
27 data Amount
28 = Amount
29 { quantity :: Quantity
30 , style :: Style
31 , unit :: Unit
32 } deriving (Data, Show, Typeable)
33
34 instance Eq Amount where
35 (==)
36 Amount{quantity=q0, unit=u0}
37 Amount{quantity=q1, unit=u1} =
38 case compare u0 u1 of
39 LT -> False
40 GT -> False
41 EQ -> (==) q0 q1 -- NOTE: MUST already be rounded to Style.precision
42
43 instance Ord Amount where
44 compare
45 Amount{quantity=q0, unit=u0}
46 Amount{quantity=q1, unit=u1} =
47 case compare u0 u1 of
48 LT -> LT
49 GT -> GT
50 EQ -> compare q0 q1 -- NOTE: MUST already be rounded to Style.precision
51
52 instance Calc.Balance.Amount Amount where
53 amount_is_zero = is_zero
54
55 -- | An 'Amount' is a partially valid 'Num' instance:
56 --
57 -- * (+) operator requires both operand to have the same 'Unit' (homogeneity constraint).
58 -- * (*) operator requires at least one operand with an empty 'Unit' ('scalar').
59 instance Num Amount where
60 abs a@Amount{quantity=q} = a{quantity=abs q}
61 fromInteger = scalar . fromInteger
62 negate a@Amount{quantity=q} = a{quantity=negate q}
63 signum a@Amount{quantity=q} = a{quantity=signum q}
64 (+) a b =
65 let s@(Style.Style{Style.precision=p}) = Style.union (style a) (style b) in
66 a{ quantity = Quantity.round p $ quantity a + quantity b
67 , style = s
68 , unit =
69 if unit a == unit b
70 then unit a
71 else error "(+) on non-homogeneous units"
72 }
73 (*) a b =
74 let Style.Style{Style.precision=p} = s in
75 a{ quantity = Quantity.round p $ quantity a * quantity b
76 , style = s
77 , unit = u
78 }
79 where (s, u) =
80 if unit a == ""
81 then
82 if unit b == ""
83 then (Style.union (style a) (style b), "")
84 else (style b, unit b)
85 else
86 if unit b == ""
87 then (style a, unit a)
88 else error "(*) by non-scalar unit"
89
90 -- ** Constructors
91
92 nil :: Amount
93 nil =
94 Amount
95 { quantity = Quantity.nil
96 , style = Style.nil
97 , unit = ""
98 }
99
100 -- *** From 'Quantity'
101
102 -- | Return an 'Amount' with 'unit' = Unit.'Unit.nil'.
103 scalar :: Quantity -> Amount
104 scalar q =
105 Amount
106 { quantity = q
107 , style = Style.Style
108 { Style.fractioning = Just '.'
109 , Style.grouping_fractional = Just $ Style.Grouping ',' [3]
110 , Style.grouping_integral = Just $ Style.Grouping ',' [3]
111 , Style.precision = maxBound
112 , Style.unit_side = Just Style.Side_Right
113 , Style.unit_spaced = Just False
114 }
115 , unit = ""
116 }
117
118 -- | <https://en.wikipedia.org/wiki/Swiss_franc Swiss franc> unit of currency.
119 chf :: Quantity -> Amount
120 chf q =
121 Amount
122 { quantity = q
123 , style = Style.Style
124 { Style.fractioning = Just ','
125 , Style.grouping_fractional = Just $ Style.Grouping '.' [3]
126 , Style.grouping_integral = Just $ Style.Grouping '.' [3]
127 , Style.precision = 2
128 , Style.unit_side = Just Style.Side_Right
129 , Style.unit_spaced = Just False
130 }
131 , unit = "CHF"
132 }
133 -- | <https://en.wikipedia.org/wiki/Yuan Yuan> unit of currency.
134 cny :: Quantity -> Amount
135 cny q =
136 Amount
137 { quantity = q
138 , style = Style.Style
139 { Style.fractioning = Just ','
140 , Style.grouping_fractional = Just $ Style.Grouping '.' [3]
141 , Style.grouping_integral = Just $ Style.Grouping '.' [3]
142 , Style.precision = 2
143 , Style.unit_side = Just Style.Side_Right
144 , Style.unit_spaced = Just False
145 }
146 , unit = "Ұ"
147 }
148 -- | <https://en.wikipedia.org/wiki/Euro Euro> unit of currency.
149 eur :: Quantity -> Amount
150 eur q =
151 Amount
152 { quantity = q
153 , style = Style.Style
154 { Style.fractioning = Just ','
155 , Style.grouping_fractional = Just $ Style.Grouping '.' [3]
156 , Style.grouping_integral = Just $ Style.Grouping '.' [3]
157 , Style.precision = 2
158 , Style.unit_side = Just Style.Side_Right
159 , Style.unit_spaced = Just False
160 }
161 , unit = "€"
162 }
163 -- | <https://en.wikipedia.org/wiki/Pound_sterling Pound sterling> unit of currency.
164 gbp :: Quantity -> Amount
165 gbp q =
166 Amount
167 { quantity = q
168 , style = Style.Style
169 { Style.fractioning = Just '.'
170 , Style.grouping_fractional = Just $ Style.Grouping ',' [3]
171 , Style.grouping_integral = Just $ Style.Grouping ',' [3]
172 , Style.precision = 2
173 , Style.unit_side = Just Style.Side_Left
174 , Style.unit_spaced = Just False
175 }
176 , unit = "£"
177 }
178 -- | <https://en.wikipedia.org/wiki/Indian_rupee Indian rupee> unit of currency.
179 inr :: Quantity -> Amount
180 inr q =
181 Amount
182 { quantity = q
183 , style = Style.Style
184 { Style.fractioning = Just ','
185 , Style.grouping_fractional = Just $ Style.Grouping '.' [3]
186 , Style.grouping_integral = Just $ Style.Grouping '.' [3]
187 , Style.precision = 2
188 , Style.unit_side = Just Style.Side_Right
189 , Style.unit_spaced = Just False
190 }
191 , unit = "₹"
192 }
193 -- | <https://en.wikipedia.org/wiki/Japanese_yen Japanese yen> unit of currency.
194 jpy :: Quantity -> Amount
195 jpy q =
196 Amount
197 { quantity = q
198 , style = Style.Style
199 { Style.fractioning = Just '.'
200 , Style.grouping_fractional = Just $ Style.Grouping ',' [3]
201 , Style.grouping_integral = Just $ Style.Grouping ',' [3]
202 , Style.precision = 2
203 , Style.unit_side = Just Style.Side_Left
204 , Style.unit_spaced = Just False
205 }
206 , unit = "¥"
207 }
208 -- | <https://en.wikipedia.org/wiki/Russian_ruble Russian ruble> unit of currency.
209 --
210 -- NOTE: Ꝑ (U+A750) is used as a replacement latin letter,
211 -- because GHC currently chokes on ₽ (U+20BD),
212 -- which is the recently (2014/02) assigned Unicode code-point
213 -- for this currency.
214 rub :: Quantity -> Amount
215 rub q =
216 Amount
217 { quantity = q
218 , style = Style.Style
219 { Style.fractioning = Just '.'
220 , Style.grouping_fractional = Just $ Style.Grouping ',' [3]
221 , Style.grouping_integral = Just $ Style.Grouping ',' [3]
222 , Style.precision = 2
223 , Style.unit_side = Just Style.Side_Left
224 , Style.unit_spaced = Just False
225 }
226 , unit = "Ꝑ"
227 }
228 -- | <https://en.wikipedia.org/wiki/United_States_dollar United States dollar> unit of currency.
229 usd :: Quantity -> Amount
230 usd q =
231 Amount
232 { quantity = q
233 , style = Style.Style
234 { Style.fractioning = Just '.'
235 , Style.grouping_fractional = Just $ Style.Grouping ',' [3]
236 , Style.grouping_integral = Just $ Style.Grouping ',' [3]
237 , Style.precision = 2
238 , Style.unit_side = Just Style.Side_Left
239 , Style.unit_spaced = Just False
240 }
241 , unit = "$"
242 }
243
244 -- ** Tests
245
246 -- | Return 'True' if and only if 'Amount'’s 'Quantity' is zero.
247 --
248 -- NOTE: the 'Amount'’s 'quantity' MUST be have been rounded at 'Amount'’s 'style'’s 'Style.precision'.
249 is_zero :: Amount -> Bool
250 is_zero = Quantity.is_zero . quantity
251
252 -- * The 'Amount_by_Unit' mapping
253
254 type Amount_by_Unit
255 = Data.Map.Map Unit Amount
256 type By_Unit = Amount_by_Unit
257
258 -- | 'Amount_by_Unit'’s is a partially valid 'Num' instance.
259 --
260 -- * (*) operator is not defined.
261 instance Num Amount_by_Unit where
262 abs = Data.Map.map (\a@Amount{quantity=q} -> a{quantity=abs q})
263 fromInteger = Data.Map.singleton "" . fromInteger
264 negate = Data.Map.map (\a@Amount{quantity=q} -> a{quantity=negate q})
265 signum = Data.Map.map (\a@Amount{quantity=q} -> a{quantity=signum q})
266 (+) = Data.Map.unionWith (+)
267 (*) = error "(*) not-supported"
268
269 type Signs = (Int, Int)
270
271 signs :: Amount_by_Unit -> Signs
272 signs = Data.Map.foldl
273 (\(nega, plus) amt ->
274 case flip compare 0 $ quantity amt of
275 LT -> (nega - 1, plus)
276 EQ -> (nega, plus)
277 GT -> (nega, plus + 1))
278 (0, 0)
279
280 -- ** Constructors
281
282 nil_By_Unit :: Amount_by_Unit
283 nil_By_Unit =
284 Data.Map.empty
285
286 -- ** Tests
287
288 -- | Return 'True' if and only if all 'Amount's satisfy 'is_zero'.
289 are_zero :: Amount_by_Unit -> Bool
290 are_zero = Data.Foldable.all is_zero
291
292 -- | Return a tuple associating the given 'Amount' with its 'Unit'.
293 assoc_by_unit :: Amount -> (Unit, Amount)
294 assoc_by_unit amount = (unit amount, amount)
295
296 -- | Return a 'Data.Map.Map' associating the given 'Amount's with their respective 'Unit'.
297 from_List :: [Amount] -> Amount_by_Unit
298 from_List amounts =
299 Data.Map.fromListWith (flip (+)) $ -- NOTE: flip to propagate 'Style' first to last.
300 Data.List.map assoc_by_unit amounts