REVISED: Wednesday, January 24, 2024
1. INTRODUCTION
This tutorial is for having fun.
2. HASKELL PROGRAM
The Haskell program is as follows:
-- C:\Users\Tinnel\Haskell2024\age.hs
import Data.List
import System.IO
main :: IO () -- Has type I/O action.
main = do { putStrLn "" -- putStrLn Has type I/O action.
; putStrLn "=========================================================="
; putStrLn ""
; putStrLn "CALCULATING YOUR AGE BY CHOCOLATE!"
; putStrLn ""
; putStrLn "First, type a positive integer from 1 to 10 indicating how"
; putStrLn "often you crave chocolate each week, then press Enter."
; cewS <- getLine -- getLine is a function, getLine :: IO String
; putStrLn ""
; let runTot1I = (read cewS)::Integer
; let runTot1S = show runTot1I
; putStrLn ("Running Total: " ++ runTot1S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; let cewI = (read cewS)::Integer
; let cewIx2I = cewI * 2
; let cewIx2S = show cewIx2I
; putStrLn ("Second, we multiply " ++ cewS ++ " by 2 which equals " ++ cewIx2S ++ ".")
; putStrLn ""
; let runTot2I = runTot1I * 2
; let runTot2S = show runTot2I
; putStrLn ("Running Total: " ++ runTot2S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; let cewIp5I = cewIx2I + 5
; let cewIp5S = show cewIp5I
; putStrLn ("Third, we add 5 to our running total which equals " ++ cewIp5S ++ ".")
; putStrLn ""
; let runTot3I = runTot2I + 5
; let runTot3S = show runTot3I
; putStrLn ("Running Total: " ++ runTot3S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; let cewIp5x50I = cewIp5I * 50
; let cewIp5x50S = show cewIp5x50I
; putStrLn ("Fourth, we multiply our running total by 50 which equals " ++ cewIp5x50S ++ ".")
; putStrLn ""
; let runTot4I = runTot3I * 50
; let runTot4S = show runTot4I
; putStrLn ("Running Total: " ++ runTot4S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; putStrLn "Fifth, type the current year date as a positive integer; e.g., 2017"
; putStrLn "then press Enter."
; yearS <- getLine -- getLine is a function, getLine :: IO String
; putStrLn ""
; putStrLn ("Running Total: " ++ runTot4S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; let yearI = (read yearS)::Integer
; let runTotI = cewIp5x50I + (yearI - 250)
; let runTotS = show runTotI
; putStrLn "Sixth, we subtract 250 from the current year; e.g., 2017 - 250 = 1767"
; putStrLn ("and add the result to our running total which equals " ++ runTotS ++ ".")
; putStrLn ""
; let runTot6I = runTot4I + (yearI - 250)
; let runTot6S = show runTot6I
; putStrLn ("Running Total: " ++ runTot6S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; putStrLn "Seventh, if you have not had your birthday this year type the integer 1."
; putStrLn "If you have had your birthday this year type zero; e.g., 0."
; putStrLn "Then press Enter."
; birthdayS <- getLine -- getLine is a function, getLine :: IO String
; putStrLn ""
; putStrLn ("Running Total: " ++ runTot6S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; let birthdayI = (read birthdayS)::Integer
; let runTotMI = (runTotI - birthdayI)
; let runTotMS = show runTotMI
; putStrLn "Eighth, we subtract 1 or 0 from the running total."
; putStrLn ""
; putStrLn ("Now our running total equals " ++ runTotMS ++ ".")
; putStrLn ""
; let runTot8I = (runTot6I - birthdayI)
; let runTot8S = show runTot8I
; putStrLn ("Running Total: " ++ runTot8S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; putStrLn "Ninth, type the year of your birth; e.g., 1992"
; putStrLn "then press Enter."
; birthYearS <- getLine -- getLine is a function, getLine :: IO String
; putStrLn ""
; putStrLn ("Running Total: " ++ runTot8S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; let birthYearI = (read birthYearS)::Integer
; let runTotBYI = (runTotMI - birthYearI)
; let runTotBYS = show runTotBYI
; putStrLn "Tenth, we subtract the year you were born from the running total."
; putStrLn ""
; putStrLn ("Now our running total equals " ++ runTotBYS ++ ".")
; putStrLn ""
; let runTot10I = (runTot8I - birthYearI)
; let runTot10S = show runTot10I
; putStrLn ("Running Total: " ++ runTot10S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
; putStrLn "The first two digits of the running total are how often you crave chocolate each week."
; putStrLn ""
; putStrLn "The last two digits of the running total is your Age By Chocolate."
; putStrLn ""
; putStrLn ("Running Total: " ++ runTot10S)
; putStrLn ""
; putStrLn "=========================================================="
; putStrLn ""
}
--
3. GHCi RUN
GHCi, version 9.8.1: http://www.haskell.org/ghc/ :? for help
Prelude> :l age
[1 of 1] Compiling Main ( age.hs, interpreted )
Ok, modules loaded: Main.
*Main> main
==========================================================
CALCULATING YOUR AGE BY CHOCOLATE!
First, type a positive integer from 1 to 10 indicating how
often you crave chocolate each week, then press Enter.
10
Running Total: 10
==========================================================
Second, we multiply 10 by 2 which equals 20.
Running Total: 20
==========================================================
Third, we add 5 to our running total which equals 25.
Running Total: 25
==========================================================
Fourth, we multiply our running total by 50 which equals 1250.
Running Total: 1250
==========================================================
Fifth, type the current year date as a positive integer; e.g., 2017
then press Enter.
2017
Running Total: 1250
==========================================================
Sixth, we subtract 250 from the current year; e.g., 2017 - 250 = 1767
and add the result to our running total which equals 3017.
Running Total: 3017
==========================================================
Seventh, if you have not had your birthday this year type the integer 1.
If you have had your birthday this year type zero; e.g., 0.
Then press Enter.
0
Running Total: 3017
==========================================================
Eighth, we subtract 1 or 0 from the running total.
Now our running total equals 3017.
Running Total: 3017
==========================================================
Ninth, type the year of your birth; e.g., 1992
then press Enter.
1992
Running Total: 3017
==========================================================
Tenth, we subtract the year you were born from the running total.
Now our running total equals 1025.
Running Total: 1025
==========================================================
The first two digits of the running total are how often you crave chocolate each week.
The last two digits of the running total is your Age By Chocolate.
Running Total: 1025
==========================================================
*Main>
4. CONCLUSION
You can have fun with Haskell.
5. REFERENCES
Bird, R. (2015). Thinking Functionally with Haskell. Cambridge, England: Cambridge University Press.
Davie, A. (1992). Introduction to Functional Programming Systems Using Haskell. Cambridge, England: Cambridge University Press.
Goerzen, J. & O'Sullivan, B. & Stewart, D. (2008). Real World Haskell. Sebastopol, CA: O'Reilly Media, Inc.
Hutton, G. (2007). Programming in Haskell. New York: Cambridge University Press.
Lipovača, M. (2011). Learn You a Haskell for Great Good!: A Beginner's Guide. San Francisco, CA: No Starch Press, Inc.
Thompson, S. (2011). The Craft of Functional Programming. Edinburgh Gate, Harlow, England: Pearson Education Limited.
In this tutorial you have seen Haskell can be used to have fun.
