Emhlabeni othakazelisayo wekhompyutha, izibali zidlala indima ebalulekile. Naphezu kokulula kwalokho okungase kufike kuqala emqondweni njengezibali - izisetshenziswa zokwenza imisebenzi ye-arithmetic - zingaba ezinye zezinto eziyinkimbinkimbi neziyinkimbinkimbi kakhulu ezikhona. Ikakhulukazi, ukuthuthukiswa kwesibali kuhilela ukucatshangelwa ngokucophelela kwama-algorithms, ukusebenzelana komsebenzisi nokulungiselelwa kokusebenza. Esinye salezo zibonelo sisolimini lokuhlela lwe-Haskell, lapho imiqondo yokuhlela esebenzayo isetshenziswa ukuze kuxazululwe izinkinga zezibalo.
Kulesi sihloko, sizohlola ukwenziwa kwesibali esiyisisekelo sisebenzisa i-Haskell. Sizohlukanisa ubunkimbinkimbi bokuhlela okusebenzayo, sinikeze imininingwane ebalulekile yemitapo yolwazi ye-Haskell nemisebenzi ehilelekile, futhi siveze indlela eya esixazululweni ngenqubo yesinyathelo nesinyathelo.
Ukuhlela Okusebenzayo Kumklamo Wokubala
Uhlelo lokusebenza lusebenzisa indlela ehlukile yokuhlela kunezilimi ezivamile eziphoqayo. Ingqikithi yokuhlela okusebenzayo ukuthi izinhlelo zakhiwa ngokusebenzisa nokubhala imisebenzi, uma kuqhathaniswa nohlelo lokusebenza oluphoqayo, oluncike kakhulu ezinguqukweni zesimo. I-Haskell, njengolimi olusebenza kahle kuphela, ikhuthaza abahleli bezinhlelo ukuthi basebenzise izinhlelo ngendlela echazayo nesezingeni eliphezulu. Ifaneleka kahle ekudalweni kwama-calculator ngenxa yokusekela kwayo ukuphathwa kwezinombolo okuyinkimbinkimbi, ukuqonda uhlu, kanye nemisebenzi ehlelekile.
Cabangela ukusebenza kwe-arithmetic yokwengeza. Ku-Haskell, umuntu angabhala umsebenzi wokwenza lo msebenzi ngale ndlela elandelayo:
addFunction :: Num a => a -> a -> a addFunction x y = x + y
Umugqa wokuqala ubizwa ngokuthi uhlobo lwesiginesha. Ihlinzeka ngezinga eliphezulu lesiqinisekiso sokuthi imisebenzi yenza njengoba ihlosiwe, ibamba amaphutha amaningi ngesikhathi sokuhlanganiswa.
Imitapo yolwazi ye-Haskell Yokusebenza Kwesibali
Enye yamandla kaHaskell iqoqo layo elibanzi lemitapo yolwazi engamathuluzi anamandla okwenza izixazululo ezinhle nezisebenza kahle. Ukwakha umshini wokubala olula, ukuqonda imitapo yolwazi emibili ebalulekile kubalulekile: Isandulelo kanye Nombhalo.Funda imitapo yolwazi.
I-Prelude ku-Haskell iwumtapo wezincwadi ozenzakalelayo ongeniswa ezinhlelweni zakho ze-Haskell. Ihlinzeka ngesethi eningi yemisebenzi yokuphatha izinhlu, izinhlamvu ezikhohlisayo, nokusebenza ngezinhlobo eziyisisekelo ezifana nama-integer nezinombolo zamaphoyinti antantayo.
Ngakolunye uhlangothi, umtapo Wombhalo.Funda unikeza umsebenzi othi “fundaMhlawumbe”, owusizo kakhulu ekufundeni okokufaka komsebenzisi ohlelweni lokubala. Ihlinzeka ngemisebenzi ephephile eyingxenye yokuguqula izintambo zibe okuguquguqukayo kwe-Haskell.
Ngala mamitapo olwazi, ukusebenza okubalulekile kwesibali kungabhalwa kalula.
Ukwakha Isibali: Ukuhlukaniswa Kwekhodi
Ukuthola phansi kuma-brass tacks, ake singene ku-nitty gritty yokubhala ngekhodi isibali esiyisisekelo kakhulu. Isikripthi esilandelayo se-Haskell sivumela umsebenzisi ukuthi afake iyunithi yezinhlamvu ze-arithmetic operation elula, futhi sibuyisela umphumela uma ukusebenza kusebenza:
import Text.Read
import Data.Maybe
calculate :: String -> Maybe Float
calculate exprString =
case words exprString of
[num1, "+", num2] -> liftA2 (+) (readMaybe num1) (readMaybe num2)
[num1, "-", num2] -> liftA2 (-) (readMaybe num1) (readMaybe num2)
[num1, "*", num2] -> liftA2 (*) (readMaybe num1) (readMaybe num2)
[num1, "/", num2] -> liftA2 (/) (readMaybe num1) (readMaybe num2)
_ -> Nothing
Umbhalo uqala ngokungenisa Umtapo Wombhalo.Funda umtapo (ngokufaka komsebenzisi) kanye neDatha.Mhlawumbe umtapo wezincwadi, ohlinzeka ngohlobo "Mhlawumbe" olusetshenziselwa ukukhombisa ukubala okungase kube yimpumelelo.
Umsebenzi wokubala uguqula umucu wokufaka ube yi-'Mhlawumbe Float', usebenzisa ukufanisa amaphethini ukuhlonza umsebenzi kanye nomsebenzi we-'liftA2' ovela kulabhulali ejwayelekile ye-Prelude ukuze usebenzise umsebenzi ezinombolweni ezihlaziyiwe. Lo msebenzi uhlanganisa izici eziyinhloko zesibali futhi ubonisa ubuhle bokuhlela okusebenzayo ekutholeni izixazululo.
Ukwandisa Ukusebenza Kwesibali
Isibali esiyisisekelo esisikhiqizile singandiswa ngezici ezengeziwe njengokuphathwa kwama-parentheses, imisebenzi yezibalo ethuthukisiwe, noma ngisho nokugcina izinto eziguquguqukayo. Ukuhlola okwengeziwe ngeHaskell namaphakheji ayo kuzoveza izindlela eziningi zokwenza isibali sibe yinkimbinkimbi, sisebenziseke futhi sibe lula ukusisebenzisa.
Ngokuqonda imiqondo ewumongo nemitapo yolwazi e-Haskell kanye nokwakhiwa kwesinyathelo nesinyathelo kwesibali esilula, umuntu angajabulela ubuhle bohlelo olusebenzayo ekubhekaneni nezinkinga zokubala. Lokhu kubili kobulula nobunkimbinkimbi yikho okwenza ukuthuthukiswa kwesibali e-Haskell kungabi nje inkinga ethokozisayo, kodwa futhi kube uhambo olufanele.
Jabulela ukubhala amakhodi nokuhlola!
