sauna-vs-gym-cost (empty) → 0.1.0

raw patch · 4 files changed

+114/−0 lines, 4 filesdep +base

Dependencies added: base

Files

• CHANGELOG.md +5/−0
• README.md +28/−0
• sauna-vs-gym-cost.cabal +36/−0
• src/SaunaVsGym/Cost.hs +45/−0

@@ -0,0 +1,5 @@+# Change log++## 0.1.0++* Initial release: utilityCost, annualSessions, sessionCost, breakEvenSessions.

@@ -0,0 +1,28 @@+# sauna-vs-gym-cost++Cost-per-session math for home recovery gear.++A home sauna's real price is not the sticker. It is the gear price+spread over the sessions a habit accrues, plus the+electricity each session draws. A $2,500 unit run four times a week at+$0.17 per kilowatt-hour lands at $25.34 a session by session 100 and+$2.84 by session 1,000, electricity included both times.++The package follows the cost-per-session method used on+[HackedSelf](https://hackedself.com). It depends only on base.++## Example++A $2,500 sauna, a $22 gym visit across town, and $0.34 of power per+session:++* per-session electricity: `utilityCost 2.0 0.17` = $0.34+* session 100 all-in: `sessionCost 2500 100 0.34` = $25.34+* session 1,000 all-in: `sessionCost 2500 1000 0.34` = $2.84+* break-even: `breakEvenSessions 2500 22 0.34` = 115.4 visits++At four sessions a week, 115.4 visits is about 6.6 months. Every gym+trip after that costs more than the power bill for a home session. If+the alternative were a $0.30 day pass, cheaper than the electricity+alone, the break-even count goes infinite: no amount of usage closes a+gap that opens the wrong way.

@@ -0,0 +1,36 @@+cabal-version:      2.2+name:               sauna-vs-gym-cost+version:            0.1.0+synopsis:           Cost-per-session math for home recovery gear+description:+  A home sauna or cold plunge is a gear price, a usage habit, and an+  electricity line. These functions spread the gear price over the+  sessions a habit accrues, add the electricity per session,+  and count the visits until the gear beats a per-visit alternative+  like a gym membership. The break-even count goes infinite when the+  alternative costs less than the electricity alone.+  .+  Companion to HackedSelf, which prices home recovery gear by+  cost-per-session math. Three pure functions on Doubles, no+  dependencies beyond base.+license:            MIT+author:             Poket Dev+maintainer:         hello@poketdev.com+homepage:           https://hackedself.com+bug-reports:        https://github.com/scrapertweeter3-prog/sauna-vs-gym-cost-hs/issues+copyright:          2026 Poket Dev LLC+category:           Math+build-type:         Simple+extra-doc-files:    README.md+                  , CHANGELOG.md++source-repository head+  type:     git+  location: https://github.com/scrapertweeter3-prog/sauna-vs-gym-cost-hs++library+  exposed-modules:  SaunaVsGym.Cost+  hs-source-dirs:   src+  build-depends:    base >=4 && <5+  default-language: Haskell2010+  ghc-options:      -Wall

@@ -0,0 +1,45 @@+-- | Cost-per-session math for home recovery gear.+--+-- A home sauna or cold plunge is a gear price, a usage habit, and an+-- electricity line. The sticker price says nothing until usage spreads+-- it over sessions and the electricity lands on each one. This module+-- restates a purchase into dollars per session and counts the visits+-- until the gear has paid for itself against a per-visit alternative+-- like a gym membership or a day pass.+module SaunaVsGym.Cost+  ( utilityCost+  , annualSessions+  , sessionCost+  , breakEvenSessions+  ) where++-- | Per-session utility cost from kilowatt-hours and the meter rate.+-- A 2 kW heater run 1 hour at $0.17/kWh is 0.34 dollars a session.+utilityCost :: Double -> Double -> Double+utilityCost kwhPerSession ratePerKwh = kwhPerSession * ratePerKwh++-- | Sessions a weekly habit adds up to over a year.+-- Four a week is 208.+annualSessions :: Double -> Double+annualSessions sessionsPerWeek = sessionsPerWeek * 52++-- | Amortized cost of one session: the gear price spread over total+-- sessions plus the electricity line. Sessions accrue as the habit+-- runs, so the same $2,500 unit lands at $25.34 by session 100 and+-- $2.84 by session 1,000 before electricity. No sessions means no+-- denominator, so the cost is infinite rather than zero.+sessionCost :: Double -> Double -> Double -> Double+sessionCost gearCost totalSessions utilityPerSession+  | totalSessions <= 0 = 1 / 0+  | otherwise          = gearCost / totalSessions + utilityPerSession++-- | Visits until the gear has paid for itself against a per-visit+-- alternative. Infinite when the alternative is cheaper than the+-- electricity alone, because usage then never closes the gap. A $22+-- gym visit against $0.34 of power needs 115.4 sessions, about 6.6+-- months at four a week, before every visit after that is free.+breakEvenSessions :: Double -> Double -> Double -> Double+breakEvenSessions gearCost alternativePerVisit utilityPerSession+  | gap <= 0  = 1 / 0+  | otherwise = gearCost / gap+  where gap   = alternativePerVisit - utilityPerSession