Rename costOfAmount -> amountCost, costOfMixedAmount -> mixedAmountCost, drop amountToCost, mixedAmountToCost.
		
			
				
	
	
		
			404 lines
		
	
	
		
			18 KiB
		
	
	
	
		
			Haskell
		
	
	
	
	
	
			
		
		
	
	
			404 lines
		
	
	
		
			18 KiB
		
	
	
	
		
			Haskell
		
	
	
	
	
	
{-|
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Convert amounts to some related value in various ways. This involves
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looking up historical market prices (exchange rates) between commodities.
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-}
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{-# LANGUAGE NamedFieldPuns #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE RecordWildCards #-}
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{-# LANGUAGE ScopedTypeVariables #-}
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{-# LANGUAGE DeriveDataTypeable, DeriveGeneric #-}
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module Hledger.Data.Valuation (
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   ValuationType(..)
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  ,PriceOracle
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  ,journalPriceOracle
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  ,unsupportedValueThenError
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  -- ,amountApplyValuation
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  -- ,amountValueAtDate
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  ,mixedAmountApplyValuation
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  ,mixedAmountValueAtDate
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  ,marketPriceReverse
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  ,priceDirectiveToMarketPrice
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  -- ,priceLookup
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  ,tests_Valuation
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)
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where
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import Control.Applicative ((<|>))
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import Control.DeepSeq (NFData)
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import Data.Data
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import Data.Decimal (roundTo)
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import Data.Function ((&), on)
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import Data.Graph.Inductive  (Gr, Node, NodeMap, mkMapGraph, mkNode, lab, out, sp)
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import Data.List
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import Data.List.Extra (nubSortBy)
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import qualified Data.Map as M
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import Data.Maybe
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import qualified Data.Text as T
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import Data.Time.Calendar (Day)
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import Data.MemoUgly (memo)
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import GHC.Generics (Generic)
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import Safe (headMay)
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import Hledger.Utils
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import Hledger.Data.Types
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import Hledger.Data.Amount
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import Hledger.Data.Dates (parsedate)
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------------------------------------------------------------------------------
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-- Types
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-- | A snapshot of the known exchange rates between commodity pairs at a given date,
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-- as a graph allowing fast lookup and path finding, along with some helper data.
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data PriceGraph = PriceGraph {
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   prGraph   :: Gr CommoditySymbol Quantity
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    -- ^ A directed graph of exchange rates between commodity pairs.
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    -- Node labels are commodities and edge labels are exchange rates,
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    -- which were either:
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    -- declared by P directives,
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    -- implied by transaction prices,
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    -- inferred by reversing a declared rate,
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    -- or inferred by reversing a transaction-implied rate.
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    -- There will be at most one edge between each directed pair of commodities,
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    -- eg there can be one USD->EUR and one EUR->USD.
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  ,prNodemap :: NodeMap CommoditySymbol
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    -- ^ Mapping of graph node ids to commodity symbols.
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  ,prDefaultValuationCommodities :: M.Map CommoditySymbol CommoditySymbol
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    -- ^ The default valuation commodity for each source commodity.
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    --   These are used when a valuation commodity is not specified
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    --   (-V). They are the destination commodity of the latest
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    --   (declared or transaction-implied, but not reverse) each
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    --   source commodity's latest market price (on the date of this
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    --   graph).
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  }
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  deriving (Show,Generic)
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instance NFData PriceGraph
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-- | A price oracle is a magic function that looks up market prices
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-- (exchange rates) from one commodity to another (or if unspecified,
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-- to a default valuation commodity) on a given date, somewhat efficiently.
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type PriceOracle = (Day, CommoditySymbol, Maybe CommoditySymbol) -> Maybe (CommoditySymbol, Quantity)
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-- | What kind of value conversion should be done on amounts ?
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-- CLI: --value=cost|then|end|now|DATE[,COMM]
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data ValuationType =
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    AtCost     (Maybe CommoditySymbol)  -- ^ convert to cost commodity using transaction prices, then optionally to given commodity using market prices at posting date
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  | AtThen     (Maybe CommoditySymbol)  -- ^ convert to default or given valuation commodity, using market prices at each posting's date
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  | AtEnd      (Maybe CommoditySymbol)  -- ^ convert to default or given valuation commodity, using market prices at period end(s)
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  | AtNow      (Maybe CommoditySymbol)  -- ^ convert to default or given valuation commodity, using current market prices
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  | AtDate Day (Maybe CommoditySymbol)  -- ^ convert to default or given valuation commodity, using market prices on some date
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  | AtDefault  (Maybe CommoditySymbol)  -- ^ works like AtNow in single period reports, like AtEnd in multiperiod reports
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  deriving (Show,Data,Eq) -- Typeable
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------------------------------------------------------------------------------
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-- Valuation
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-- | Apply a specified valuation to this mixed amount, using the
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-- provided price oracle, commodity styles, reference dates, and
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-- whether this is for a multiperiod report or not.
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-- See amountApplyValuation.
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mixedAmountApplyValuation :: PriceOracle -> M.Map CommoditySymbol AmountStyle -> Day -> Maybe Day -> Day -> Bool -> ValuationType -> MixedAmount -> MixedAmount
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mixedAmountApplyValuation priceoracle styles periodlast mreportlast today ismultiperiod v (Mixed as) =
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  Mixed $ map (amountApplyValuation priceoracle styles periodlast mreportlast today ismultiperiod v) as
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-- | Apply a specified valuation to this amount, using the provided
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-- price oracle, reference dates, and whether this is for a
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-- multiperiod report or not. Also fix up its display style using the
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-- provided commodity styles.
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--
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-- When the valuation requires converting to another commodity, a
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-- valuation (conversion) date is chosen based on the valuation type,
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-- the provided reference dates, and whether this is for a
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-- single-period or multi-period report. It will be one of:
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--
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-- - a fixed date specified by the ValuationType itself
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--   (--value=DATE).
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-- 
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-- - the provided "period end" date - this is typically the last day
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--   of a subperiod (--value=end with a multi-period report), or of
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--   the specified report period or the journal (--value=end with a
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--   single-period report).
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--
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-- - the provided "report end" date - the last day of the specified
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--   report period, if any (-V/-X with a report end date).
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--
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-- - the provided "today" date - (--value=now, or -V/X with no report
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--   end date).
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-- 
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-- Note --value=then is not supported by this function, and will cause an error;
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-- use postingApplyValuation for that.
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-- 
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-- This is all a bit complicated. See the reference doc at
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-- https://hledger.org/hledger.html#effect-of-value-on-reports
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-- (hledger_options.m4.md "Effect of --value on reports"), and #1083.
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--
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amountApplyValuation :: PriceOracle -> M.Map CommoditySymbol AmountStyle -> Day -> Maybe Day -> Day -> Bool -> ValuationType -> Amount -> Amount
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amountApplyValuation priceoracle styles periodlast mreportlast today ismultiperiod v a =
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  case v of
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    AtCost    Nothing            -> styleAmount styles $ amountCost a
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    AtCost    mc                 -> amountValueAtDate priceoracle styles mc periodlast $ styleAmount styles $ amountCost a
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    AtThen    _mc                -> error' unsupportedValueThenError  -- TODO
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                                 -- amountValueAtDate priceoracle styles mc periodlast a  -- posting date unknown, handle like AtEnd
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    AtEnd     mc                 -> amountValueAtDate priceoracle styles mc periodlast a
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    AtNow     mc                 -> amountValueAtDate priceoracle styles mc today a
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    AtDefault mc | ismultiperiod -> amountValueAtDate priceoracle styles mc periodlast a
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    AtDefault mc                 -> amountValueAtDate priceoracle styles mc (fromMaybe today mreportlast) a
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    AtDate d  mc                 -> amountValueAtDate priceoracle styles mc d a
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-- | Standard error message for a report not supporting --value=then.
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unsupportedValueThenError :: String
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unsupportedValueThenError = "Sorry, --value=then is not yet implemented for this kind of report."
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-- | Find the market value of each component amount in the given
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-- commodity, or its default valuation commodity, at the given
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-- valuation date, using the given market price oracle.
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-- When market prices available on that date are not sufficient to
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-- calculate the value, amounts are left unchanged.
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mixedAmountValueAtDate :: PriceOracle -> M.Map CommoditySymbol AmountStyle -> Maybe CommoditySymbol -> Day -> MixedAmount -> MixedAmount
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mixedAmountValueAtDate priceoracle styles mc d (Mixed as) = Mixed $ map (amountValueAtDate priceoracle styles mc d) as
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-- | Find the market value of this amount in the given valuation
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-- commodity if any, otherwise the default valuation commodity, at the
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-- given valuation date. (The default valuation commodity is the
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-- commodity of the latest applicable market price before the
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-- valuation date.)
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--
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-- The returned amount will have its commodity's canonical style applied,
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-- but with the precision adjusted to show all significant decimal digits
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-- up to a maximum of 8. (experimental)
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--
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-- If the market prices available on that date are not sufficient to
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-- calculate this value, the amount is left unchanged.
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amountValueAtDate :: PriceOracle -> M.Map CommoditySymbol AmountStyle -> Maybe CommoditySymbol -> Day -> Amount -> Amount
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amountValueAtDate priceoracle styles mto d a =
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  case priceoracle (d, acommodity a, mto) of
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    Nothing           -> a
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    Just (comm, rate) ->
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      -- setNaturalPrecisionUpTo 8 $  -- XXX force higher precision in case amount appears to be zero ?
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                                      -- Make default display style use precision 2 instead of 0 ?
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                                      -- Leave as is for now; mentioned in manual.
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      styleAmount styles
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      amount{acommodity=comm, aquantity=rate * aquantity a}
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------------------------------------------------------------------------------
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-- Market price lookup
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-- From a journal's directive-declared and transaction-implied market
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-- prices, generate a memoising function that efficiently looks up
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-- exchange rates between commodities on any date. For best performance,
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-- you should generate this only once per journal, reusing it across
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-- reports if there are more than one (as in compoundBalanceCommand).
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journalPriceOracle :: Journal -> PriceOracle
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journalPriceOracle Journal{jpricedirectives, jtransactionimpliedmarketprices} =
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  -- traceStack "journalPriceOracle" $
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  let
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    pricesatdate =
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      memo $
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      pricesAtDate jpricedirectives jtransactionimpliedmarketprices
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  in
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    memo $
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    uncurry3 $
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    priceLookup pricesatdate
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-- | Given a list of price directives in parse order, find the market
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-- value at the given date of one unit of a given source commodity, in
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-- a different specified valuation commodity, or a default valuation
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-- commodity.
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--
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-- When the valuation commodity is specified, this looks for an
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-- exchange rate (market price) calculated in any of the following
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-- ways, in order of preference:
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--
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-- 1. a declared market price (DMP) - a P directive giving the
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--    exchange rate from source commodity to valuation commodity
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--
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-- 2. a transaction-implied market price (TMP) - a market price
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--    equivalent to the transaction price used in the latest
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--    transaction from source commodity to valuation commodity
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--    (on or before the valuation date)
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--
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-- 3. a reverse declared market price (RDMP) - calculated by inverting
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--    a DMP
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--
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-- 4. a reverse transaction-implied market price (RTMP) - calculated
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--    by inverting a TMP
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--
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-- 5. an indirect market price (IMP) - calculated by combining the
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--    shortest chain of market prices (any of the above types) leading
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--    from source commodity to valuation commodity.
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--
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-- When the valuation commodity is not specified, this looks for the
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-- latest applicable declared or transaction-implied price, and
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-- converts to the commodity mentioned in that price (the default
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-- valuation commodity).
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--
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-- Note this default valuation commodity can vary across successive
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-- calls for different dates, since it depends on the price
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-- declarations in each period.
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--
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-- This returns the valuation commodity that was specified or
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-- inferred, and the quantity of it that one unit of the source
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-- commodity is worth. Or if no applicable market price or chain of
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-- prices can be found, or the source commodity and the valuation
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-- commodity are the same, returns Nothing.
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--
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priceLookup :: (Day -> PriceGraph) -> Day -> CommoditySymbol -> Maybe CommoditySymbol -> Maybe (CommoditySymbol, Quantity)
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priceLookup pricesatdate d from mto =
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  -- trace ("priceLookup ("++show d++", "++show from++", "++show mto++")") $
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  let
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    -- build a graph of the commodity exchange rates in effect on this day
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    -- XXX should hide these fgl details better
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    PriceGraph{prGraph=g, prNodemap=m, prDefaultValuationCommodities=defaultdests} = pricesatdate d
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    fromnode = node m from
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    mto' = mto <|> mdefaultto
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      where
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        mdefaultto = dbg4 ("default valuation commodity for "++T.unpack from) $
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                     M.lookup from defaultdests
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  in
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    case mto' of
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      Nothing            -> Nothing
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      Just to | to==from -> Nothing
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      Just to            ->
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        -- We have a commodity to convert to. Find the most direct price available.
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        case mindirectprice of
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          Nothing -> Nothing
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          Just q  -> Just (to, q)
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        where
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          tonode = node m to
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          mindirectprice :: Maybe Quantity =
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            -- Find the shortest path, if any, between from and to.
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            case sp fromnode tonode g :: Maybe [Node] of
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              Nothing    -> Nothing
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              Just nodes ->
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                dbg ("market price "++intercalate "->" (map T.unpack comms)) $
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                Just $ product $ pathEdgeLabels g nodes  -- convert to a single exchange rate
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                where comms = catMaybes $ map (lab g) nodes
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          -- log a message and a Maybe Quantity, hiding Just/Nothing and limiting decimal places
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          dbg msg = dbg4With (((msg++": ")++) . maybe "" (show . roundTo 8))
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tests_priceLookup =
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  let
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    d = parsedate
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    a q c = amount{acommodity=c, aquantity=q}
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    p date from q to = PriceDirective{pddate=d date, pdcommodity=from, pdamount=a q to}
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    ps1 = [
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       p "2000/01/01" "A" 10 "B"
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      ,p "2000/01/01" "B" 10 "C"
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      ,p "2000/01/01" "C" 10 "D"
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      ,p "2000/01/01" "E"  2 "D"
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      ,p "2001/01/01" "A" 11 "B"
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      ]
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    pricesatdate = pricesAtDate ps1 []
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  in test "priceLookup" $ do
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    priceLookup pricesatdate (d "1999/01/01") "A" Nothing    @?= Nothing
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    priceLookup pricesatdate (d "2000/01/01") "A" Nothing    @?= Just ("B",10)
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    priceLookup pricesatdate (d "2000/01/01") "B" (Just "A") @?= Just ("A",0.1)
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    priceLookup pricesatdate (d "2000/01/01") "A" (Just "E") @?= Just ("E",500)
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------------------------------------------------------------------------------
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-- Building the price graph (network of commodity conversions) on a given day.
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-- | Convert a list of market price directives in parse order, and a
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-- list of transaction-implied market prices in parse order, to a
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-- graph of the effective exchange rates between commodity pairs on
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-- the given day.
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pricesAtDate :: [PriceDirective] -> [MarketPrice] -> Day -> PriceGraph
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pricesAtDate pricedirectives transactionimpliedmarketprices d =
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  -- trace ("pricesAtDate ("++show d++")") $
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  PriceGraph{prGraph=g, prNodemap=m, prDefaultValuationCommodities=defaultdests}
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  where
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    declaredandimpliedprices = latestPriceForEachPairOn pricedirectives transactionimpliedmarketprices d
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    -- infer any additional reverse prices not already declared or implied
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    reverseprices =
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      dbg5 "reverseprices" $
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      map marketPriceReverse declaredandimpliedprices \\ declaredandimpliedprices
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    -- build the graph and associated node map
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    (g, m) =
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      mkMapGraph
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      (dbg5 "g nodelabels" $ sort allcomms) -- this must include all nodes mentioned in edges
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      (dbg5 "g edges"      $ [(mpfrom, mpto, mprate) | MarketPrice{..} <- prices])
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      :: (Gr CommoditySymbol Quantity, NodeMap CommoditySymbol)
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      where
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        prices   = declaredandimpliedprices ++ reverseprices
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        allcomms = map mpfrom prices
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    -- save the forward prices' destinations as the default valuation
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    -- commodity for those source commodities
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    defaultdests = M.fromList [(mpfrom,mpto) | MarketPrice{..} <- declaredandimpliedprices]
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-- From a list of price directives in parse order, and a list of
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-- transaction-implied market prices in parse order, get the effective
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-- price on the given date for each commodity pair. That is, the
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-- latest declared or transaction-implied price dated on or before
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-- that day, with declared prices taking precedence.
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latestPriceForEachPairOn :: [PriceDirective] -> [MarketPrice] -> Day -> [MarketPrice]
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latestPriceForEachPairOn pricedirectives transactionimpliedmarketprices d =
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  dbg5 "latestPriceForEachPairOn" $
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  let
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    -- consider only declarations/transactions before the valuation date
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    declaredprices = map priceDirectiveToMarketPrice $ filter ((<=d).pddate) pricedirectives
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    transactionimpliedmarketprices' = filter ((<=d).mpdate) transactionimpliedmarketprices
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    -- label the items with their precedence and then their parse order
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    declaredprices'                  = [(1, i, p) | (i,p) <- zip [1..] declaredprices]
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    transactionimpliedmarketprices'' = [(0, i, p) | (i,p) <- zip [1..] transactionimpliedmarketprices']
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  in
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    -- combine
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    declaredprices' ++ transactionimpliedmarketprices''
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    -- sort by newest date then highest precedence then latest parse order
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    & sortBy (flip compare `on` (\(precedence,parseorder,mp)->(mpdate mp,precedence,parseorder)))
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    -- discard the sorting labels
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    & map third3
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    -- keep only the first (ie the newest, highest precedence and latest parsed) price for each pair
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    & nubSortBy (compare `on` (\(MarketPrice{..})->(mpfrom,mpto)))
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priceDirectiveToMarketPrice :: PriceDirective -> MarketPrice
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priceDirectiveToMarketPrice PriceDirective{..} =
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  MarketPrice{ mpdate = pddate
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             , mpfrom = pdcommodity
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             , mpto   = acommodity pdamount
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             , mprate = aquantity pdamount
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             }
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marketPriceReverse :: MarketPrice -> MarketPrice
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marketPriceReverse mp@MarketPrice{..} = mp{mpfrom=mpto, mpto=mpfrom, mprate=1/mprate}
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------------------------------------------------------------------------------
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-- fgl helpers
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-- | Look up an existing graph node by its label.
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-- (If the node does not exist, a new one will be generated, but not
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-- persisted in the nodemap.)
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node :: Ord a => NodeMap a -> a -> Node
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node m = fst . fst . mkNode m
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-- | Convert a valid path within the given graph to the corresponding
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-- edge labels. When there are multiple edges between two nodes, the
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-- lowest-sorting label is used.
 | 
						|
pathEdgeLabels :: (Show b, Ord b) => Gr a b -> [Node] -> [b]
 | 
						|
pathEdgeLabels g = map frommaybe . map (nodesEdgeLabel g) . pathEdges
 | 
						|
  where frommaybe = fromMaybe (error' "pathEdgeLabels: expected no Nothings here")
 | 
						|
 | 
						|
-- | Convert a path to node pairs representing the path's edges.
 | 
						|
pathEdges :: [Node] -> [(Node,Node)]
 | 
						|
pathEdges p = [(f,t) | f:t:_ <- tails p]
 | 
						|
 | 
						|
-- | Get the label of a graph edge from one node to another.
 | 
						|
-- When there are multiple such edges, the lowest-sorting label is used.
 | 
						|
nodesEdgeLabel :: Ord b => Gr a b -> (Node, Node) -> Maybe b
 | 
						|
nodesEdgeLabel g (from,to) = headMay $ sort [l | (_,t,l) <- out g from, t==to]
 | 
						|
 | 
						|
------------------------------------------------------------------------------
 | 
						|
 | 
						|
tests_Valuation = tests "Valuation" [
 | 
						|
   tests_priceLookup
 | 
						|
  ]
 |