From 1f29b55821277fa11109a90a9a9753d62b81ae33 Mon Sep 17 00:00:00 2001
From: Ari Angga Nugraha <ari.angga@ui.ac.id>
Date: Sat, 26 Dec 2020 00:24:27 +0700
Subject: [PATCH] add comment
---
src/NetPresentValue.hs | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/src/NetPresentValue.hs b/src/NetPresentValue.hs
index c8469da..af73ac8 100644
--- a/src/NetPresentValue.hs
+++ b/src/NetPresentValue.hs
@@ -28,20 +28,26 @@ data InputNetPresentValue = InputNetPresentValue
calculateNetPresentValue :: InputNetPresentValue -> Double
calculateNetPresentValue inputNetPresentValue = netPresentValue inputNetPresentValue
+-- high order function
netPresentValue inputNetPresentValue = foldl (+) 0 pv
where
pv = presentValue inputNetPresentValue
+-- high order function
presentValue inputNetPresentValue = zipWith (*) (netcashflow income outcome) (factorpresentvalue (project_interest inputNetPresentValue))
where
income = [income_1 inputNetPresentValue, income_2 inputNetPresentValue, income_3 inputNetPresentValue, income_4 inputNetPresentValue, income_5 inputNetPresentValue]
outcome = [outcome_1 inputNetPresentValue, outcome_2 inputNetPresentValue, outcome_3 inputNetPresentValue, outcome_4 inputNetPresentValue, outcome_5 inputNetPresentValue]
-netcashflow a b = zipWith (-) a b
+-- currying
+netcashflow = zipWith (-)
+-- recursion
power n 1 = n
power n m = n * (power n (m-1))
+-- recursion
powervalue interest n = 1 / (power (1 + interest) n)
+-- high order function
factorpresentvalue interest = map (\x -> powervalue interest x) [1..5]
--
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