Haskell入門ハンズオン

)BTLFMMೖ໳ϋϯζΦϯ ʙ3&1-Ͱ࢝ΊΔ)BTLFMMੜ׆ʙ "SVOFLP!)BTLFMMKQ

ࣗݾ঺հ w !BSVOFLP w Ұൠࣾஂ๏ਓ-0$"-ֶੜ෦ w ߴߍੜ͙Β͍ͷ࣌ʹ)BTLFMMʹग़ձͬͯ͠·ͬͨ w )BTLFMMKQͷ4MBDLʹજ෬த

)BTLFMMKQͷ͝঺հ w ೔ຊ)BTLFMMϢʔβʔάϧʔϓ w ೔ຊʹ͓͚Δ)BTLFMMͷීٴ׆ಈͱར༻ऀͷαϙʔτΛ࣮ࢪ w 4MBDL΋͋ΔͷͰͥͻ͝ࢀՃ͍ͩ͘͞ʂʂ

શମͷྲྀΕ

໨ඪ w ԿΒ͔ͷݴޠΛ΍ͬͨ͜ͱ͕͋Δਓ͕ w ͪΐͬͱ͚ͩͰ΋)BTLFMMʹ਌͠ΈΛ࣋ͯΔΑ͏ʹͳΔʂ

ຊ೔ͷϝχϡʔ )BTLFMMͷઆ໌ ؀ڥߏஙʹ͍ͭͯ 3&1-Ͱ༡Ϳ ࿅श໰୊৭ʑ

ࢀߟจݙ w ͍͢͝)BTLFMMͨͷֶ͘͠΅͏ w .JSBO-JQPWB㶜Bஶ w ాதӳߦ༁ w ଜओਸߦ༁ w
)BTLFMMͷΤοηϯε͕٧·ͬͨຊͰ͢ʂ

)BTLFMMͬͯͲΜͳݴޠʁ

)BTLFMMͬͯͲΜͳݴޠʁ w ʮ७ਮؔ਺ܕϓϩάϥϛϯάݴޠʯ w ७ਮ w ࡞༻ͱ෭࡞༻͕෼཭͞Ε͍ͯΔঢ়ଶ w ࢀরಁաੑ͕อূ͞Ε͓ͯΓɺಉ͡Ҿ਺Λ༩͑ͨؔ਺͸͍ͭݺΜͰ΋ಉ݁͡Ռ Λฦ͢
w ؔ਺ܕϓϩάϥϛϯά w ϓϩάϥϜશମΛؔ਺ͷ૊Έ߹ΘͤͰهड़͢ΔϓϩάϥϛϯάελΠϧͷ͜ͱ

)BTLFMMͬͯͲΜͳݴޠʁ w σϑΥϧτͰ஗ԆධՁ w ஋͕ਅʹඞཁʹͳΔ·ͰධՁ͞Εͳ͍ w ৔߹ʹΑͬͯ͸ϝϦοτͰɺ৔߹ʹΑͬͯ͸σϝϦοτ w ڧ͍੩తܕ෇͚ w
͍͍ͨͯͷ৔߹ܕਪ࿦ͷ͓͔͛ͰܕΛ໌ࣔ͢Δඞཁ͸ແ͍ w Ͱ΋ॻ͘ͱ͖͸ܕΛҙࣝͭͭ͠ॻ͘ͱॻ͖΍͍͢ w ॲཧͷࣦഊ΍*0ͳͲ΋ܕͰද͢

؀ڥߏங

4UBDLΛ࢖͏ w )BTLFMM؀ڥ͸ʮ4UBDLʯΛ࢖ͬͯߏங w +BWBͷ.BWFO΍4DBMBͷTCUʹ͋ͨΔϏϧυπʔϧ w )BTLFMMίϯύΠϥͷσϑΝΫτελϯμʔυͰ͋Δ  ()$ͷ҆ఆ൛͕Πϯετʔϧ͞ΕΔ w ϓϩδΣΫτ͝ͱʹύοέʔδͷ؅ཧ͕Մೳ
w ͨͩ͠()$ͷ༰ྔ͕େ͖͍ͷͰɺࠓճ͸঺հ͚ͩ

4UBDLͷΠϯετʔϧ w 6OJYܥ04Ͱ͋Ε͹ɺΠϯετʔϧ͸ҎԼͷίϚϯυҰൃͰऴྃ w ৄࡉ͸ެࣜαΠτΛ͝ཡ͍ͩ͘͞ w IUUQTEPDTIBTLFMMTUBDLPSHFOTUBCMF3&"%.& $ curl -sSL
https://get.haskellstack.org/ | sh

4UBDLΛ࢖͏ w ॳճ͸·ͣΞοϓσʔτΛ͠ɺ4UBDLBHF͔Β࠷৽ͷ-54Λऔಘ w 4UBDLBHF͸)BTLFMMύοέʔδͷ҆ఆ൛όʔδϣϯΛूΊͨϦϙδτϦ w Ξοϓσʔτ͕Ͱ͖ͨΒ3&1- ()$J Λىಈ $
stack update $ stack ghci

ΦϯϥΠϯ3&1- w ࠓճ͸4UBDL ()$Jͷ୅ΘΓʹΦϯϥΠϯ3&1-ͷSFQMJUΛར༻ w IUUQTSFQMJUMBOHVBHFTIBTLFMM w ը໘ࠨ͕ΤσΟλɺӈ͕()$J

()$JͰ༡Ϳ

͜ͷηΫγϣϯͰ΍Δ͜ͱ w ()$Jʹ؆୯ͳࣜΛଧͪࠐΜͰి୎୅ΘΓʹ࢖͑ΔΑ͏ʹͳΔ w #PPMԋࢉ͕Ͱ͖Δ

()$JͰి୎ w Α͋͘Δதஔԋࢉࢠ͕ར༻Մೳ w w )BTLFMMతʹ͸தஔؔ਺ͱݺͼ·͢
w ΧοίͳͲ΋ͦͷ·· w ͨͩ͠ϚΠφεͷ஋͸ׅހΛ෇͚ͯ໌ࣔ w ಛఆͷ৚݅ͰύʔεΤϥʔʹͳΓ·͢ > 1 + 1 2 > (2 + 4) / 2 3.0 > 2 * 10 / 5 4.0 > 10 - 100 -90 > -10 + 20 10 > 20 - (-10) 30 > 20 - -10 Precedence parsing error

()$JͰ#PPMԋࢉ w ଞͷݴޠͱ͍͍ͩͨҰॹ w ൱ఆ͚ͩ஫ҙʂʂ > 'a' == 'a' True
> 1 /= 1 False > True && False False > False || True True > not True False

͜͜·Ͱͷ·ͱΊ w ଞͷݴޠͱ΄΅มΘΒͳ͍࢛ଇԋࢉ͕Մೳ w #PPMԋࢉ΋΄΅ಉ༷͚ͩͲɺ൱ఆͷܗʹ஫ҙ

ؔ਺Λ࢖͏ɾ࡞Δ

͜ͷηΫγϣϯͰ΍Δ͜ͱ w )BTLFMMಛ༗ͷؔ਺ݺͼग़͠ΛֶͿ w தஔؔ਺ͱલஔؔ਺ͷม׵ΛֶͿ w ݁߹ॱংΛֶͿ

ؔ਺ͷݺͼํ w Ҿ਺Λεϖʔε۠੾ΓͰࢦఆ͢Δ͚ͩ w Ҿ਺ؔ਺ͷ৔߹͸όοΫΫΥʔτͰғΜͰதஔܗࣜʹ΋Ͱ͖Δ w ٯʹதஔؔ਺͸ׅހͰғΉͱҾ਺ؔ਺ԽͰ͖Δ > mod
10 3 1 > 10 `mod` 3 1 > (+) 1 2 3

ؔ਺ͷݺͼํ w ݁߹ॱং͸ؔ਺ద༻͕࠷ڧͳͷͰదٓΧοίΛ࢖͏ w ͔ͦ͜ΒޙΖશ෦ΛׅހʹೖΕ͍ͨ৔߹͸ʮʯ͕ศར > sin (pi /
2) 1.0 > sin $ pi / 2 1.0

ܭࢉ݁Ռͷอଘ w ()$JͰ͸ɺΠίʔϧΛ࢖ͬͯద౰ͳม਺ʹ஋Λଋറ͢Δ͜ͱ͕Մೳ w ()$J͡Όͳ͍ͱ͜ΖͰ͸ͪΐͬͱҧ͏ͷͰ஫ҙ > hoge = 1 >
hoge 1 > fuga = sin $ pi / 2 > fuga 1.0

ؔ਺Λ࡞Δ w Ҿ਺Λεϖʔε۠੾ΓͰॻ͍ͯ͋͛Ε͹0, w )BTLFMM͸ࣜࢦ޲ͰͲΜͳؔ਺΋ৗʹ஋Λฦ͢ͷͰSFUVSO͸ෆཁ w ෆཁͱ͍͏͔ͦ΋ͦ΋SFUVSOΛॻ͚ͳ͍ w ࡾฏํͷఆཧΛॻ͍ͯΈΔ >
calcDistance x1 y1 x2 y2 = sqrt $ (x1 - x2) ^ 2 + (y1 - y2) ^ 2 > calcDistance 0 0 1 1 1.4142135623730951 > calcDistance 0 0 1 (sqrt 3) 1.9999999999999998 a2 + b2 = c2

͜͜·Ͱͷ·ͱΊ w ؔ਺ݺͼग़͠͸Ҿ਺Λεϖʔε۠੾ΓͰ w Χοί ͱAόοΫΫΥʔτAͰલஔͱதஔʹม׵ w ݁߹ॱং͸ؔ਺͕࠷ڧ w దٓΧοί΍Λ࢖ͬͯ༏ઌॱҐΛ੍ޚ
w ؔ਺ఆٛ΋Ҿ਺Λεϖʔε۠੾ΓͰ w ͨͩ͠SFUVSO͸͍Βͳ͍

ϦετͰ༡Ϳ

͜ͷηΫγϣϯͰ΍Δ͜ͱ w Ϧετͷఆٛํ๏ w ϨϯδΛ࢖ͬͨϦετͷҰׅੜ੒ w Ϧετͷܨ͗ํ w Ϧετૢ࡞ؔ਺ w
ແݶϦετ

ϦετΛ࡞Δ w Α͘ݟΔײ͡ͷϦςϥϧͰॻ͚Δ w ൣғ Ϩϯδ ੜ੒΋Մೳ ॱ൪͕͋Δ΋ͷͳΒԿͰ΋0, w
ॳظ஋ͱ൪໨ͷ஋ΛΧϯϚ۠੾ΓͰॻ͚͹౳ࠩ਺ྻ΋0, > l = [1, 3, 5, 7, 9] > l [1,3,5,7,9] > [1..10] [1,2,3,4,5,6,7,8,9,10] > ['a'..'g'] "abcdefg" > [1,4..20] [1,4,7,10,13,16,19]

ϦετΛܨ͙ w ϦετͱϦετΛܨ͙ʹ͸ Λ࢖͏ w ୯ํ޲ϦετͷͨΊڊେϦετʹܨ͝͏ͱ͢Δͱஶ͘͠஗͍ͷͰ஫ҙ w ઌ಄ʹͭ෇͚଍͍ͨ͠ͱ͖͸ίϩϯΛ࢖͏ w ຤ඌʹ͸෇͚଍ͤͳ͍ͷͰ஫ҙ
Prelude> [1..5] ++ [4..10] [1,2,3,4,5,4,5,6,7,8,9,10] Prelude> 5:[6..10] [5,6,7,8,9,10]

Ϧετૢ࡞ؔ਺ w ઌ಄ΛऔΓग़͢ w ઌ಄Ҏ֎ΛऔΓग़͢ w ຤ඌҎ֎ΛऔΓग़͢ w ຤ඌΛऔΓग़͢ >
head [1..5] 1 > tail [1..5] [2,3,4,5] > init [1..5] [1,2,3,4] > last [1..5] 5

ແݶϦετ w )BTLFMM͸σϑΥϧτͰ஗ԆධՁͳͷͰແݶϦετ͕࡞੒Մೳ w Ϩϯδͷ຤ඌΛল͘ͱແݶϦετʹͳΔ w ద౰ʹʮ$USM $ʯͰࢭΊ͍ͯͩ͘͞ w Ͳ͔͜ͰධՁ͕Ұҙʹఆ·ΔΑ͏ͳؔ਺ͱ૊Έ߹ΘͤΔ͜ͱ΋Մೳ
> [1..] [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,…… > head [1..] 1

͜͜·Ͱͷ·ͱΊ w ͋Γ͕ͪͳํ๏ͰϦετΛఆٛՄೳ w ϨϯδͰϦετΛҰׅੜ੒ w Ϧετಉ࢜͸ Ͱɺઌ಄ʹ͚ͭͩͳΒͰܨ͙ w Ϧετૢ࡞ؔ਺Λศརʹ࢖ͬͯ஋ΛऔΓग़͢
w Ϩϯδ͸ແݶϦετ΋ੜ੒Մೳ

ܕͱΊ͙Δ)BTLFMMੈք

͜ͷηΫγϣϯͰ΍Δ͜ͱ w ܕͷௐ΂ํ w ܕͷදهํ๏ w ܕม਺ w தஔؔ਺ͷܕ w
ܕΫϥε

ܕΛௐ΂Δ w )BTLFMM͸ͱʹ͔͘ܕΛҙࣝ͢Δͱॻ͖΍͍͢ w ()$JͰܕΛௐ΂Δʹ͸ʮUʯίϚϯυΛར༻ > :t 'a' 'a' ::
Char > :t False False :: Bool

ܕͷදهͱม਺ w )BTLFMMͰ͸ԾҾ਺໊ͱܕ͸ผʑʹఆٛ w ܕఆٛ͸Ҿ਺ͷܕͱฦΓ஋ͷܕΛಛʹ۠ผͤͣͰ۠੾ͬͯఆٛ w IFBE΍UBJMͷܕΛௐ΂Δͱग़ͯ͘ΔzBz͕ܕม਺ w Ҿ਺ͱฦΓ஋Ͱܕ͸ಉ͡Ͱ͋ͬͯཉ͍͚͠ͲͲΜͳܕͰ΋0, >
:t head head :: [a] -> a > :t tail tail :: [a] -> [a]

தஔؔ਺ͷܕΛௐ΂Δ w தஔؔ਺ͷܕΛௐ΂Δͱ͖͸ΧοίͰ͘͘Δ w ଍͠ࢉͷྫ w ͜ͷ͸ԿͩΖ͏ʁ > :t (+)
(+) :: Num a => a -> a -> a

ܕΫϥεͱܕม਺ w /VN͸਺஋શൠΛද͢ܕΫϥε w ܕΛ෼ྨ͢ΔͨΊͷ࢓૊Έ w /VNB͸ʮB͸/VNͷΠϯελϯεʯͱ͍͏੍໿Λҙຯ͢Δ w ٯʹݴ͏ͱʮB͸/VNͳΒͳΜͰ΋͍͍ʯͱ΋ղऍՄೳ w
/VNͷΠϯελϯεͱͯ͠*OU΍%PVCMF͕ఆٛ͞Ε͍ͯΔ (+) :: Num a => a -> a -> a

͜͜·Ͱͷ·ͱΊ w UίϚϯυͰܕ͕ௐ΂ΒΕΔ w ԾҾ਺ͱܕ͸ผʑʹఆٛ w ͰԾҾ਺ͷܕͱฦΓ஋ͷܕΛ۠੾ͬͯॻ͘ w ܕม਺Λ࢖ͬͯ͏·͘ந৅Խ w
தஔؔ਺ͷܕΛௐ΂Δͱ͖͸ Χοί Λ࢖͏ w ܕΛ·ͱΊΔͨΊʹܕΫϥε͕࢖͑Δ

ؔ਺ͷਂ۷Γ

͜ͷηΫγϣϯͰ΍Δ͜ͱ w ΧϦʔԽ w ߴ֊ؔ਺ w ߹੒ؔ਺

ؔ਺ͷΧϦʔԽ w )BTLFMMͷؔ਺͸σϑΥϧτͰΧϦʔԽ͞ΕΔ w Ҿ਺Λऔͬͯʮ࢒ΓͷҾ਺ΛऔͬͯฦΓ஋Λฦؔ͢਺ʯΛฦ͢ w ؔ਺ͷ෦෼ద༻͕ՄೳʹͳΔ > :t gcd
gcd :: Integral a => a -> a -> a > gcdOfFiveAnd = gcd 5 > :t gcdOfFiveAnd gcdOfFiveAnd :: Integral a => a -> a > gcdOfFiveAnd 13 1

ߴ֊ؔ਺ w ؔ਺ΛҾ਺ʹऔΔؔ਺Λߴ֊ؔ਺ͱݺͿ w Ҿ਺ʹؔ਺Λ౉͢ͱ͖͸ϥϜμࣜΛ࢖͏ w Ͱ΋ΧϦʔԽ͞ΕΔ͜ͱΛࢥ͍ग़͢ͱ΋ͬͱศར > :t map
map :: (a -> b) -> [a] -> [b] > map (\x -> mod 10 x) [1, 2, 3] [0,0,1] > map (mod 10) [1, 2, 3] [0,0,1]

߹੒ؔ਺ w ਺ֶͷ࣌ؒʹ΍ͬͨ͋ͷҾ਺ؔ਺ͷ߹੒ؔ਺͸ʮʯͰදݱ w ଟҾ਺ؔ਺͸෦෼ద༻ͯ͠Ҿ਺ؔ਺ʹ͢Ε͹߹੒Մೳ g(f(x)) = (g ∘ f)(x)
> cos . sin $ pi 1.0 cos(sin(x)) = (cos ∘ sin)(x) > sum . map (+ 1) . filter (> 5) $ [3, 4, 5, 6, 7] 15

͜͜·Ͱͷ·ͱΊ w )BTLFMMͷؔ਺͸σϑΥϧτͰΧϦʔԽ͞Ε͍ͯΔ w ؔ਺ΛҾ਺ʹऔΔؔ਺͕ߴ֊ؔ਺ w lzͰؔ਺͕߹੒Մೳ

λϓϧͰ༡Ϳ

͜ͷηΫγϣϯͰ΍Δ͜ͱ w λϓϧͱ͸ʁ w Ϧετ͔ΒλϓϧΛੜ੒ w ϥϜμࣜͰλϓϧΛ࢖͏ʹ͸

λϓϧͱ͸ʁ w λϓϧ͸ݻఆ௕ͷ೚ҙͷ஋ͷ૊ w Ϧετ͸୯ҰܕͰ͔͠࡞Εͳ͍͕λϓϧ͸ෳ਺ͷܕ͔Β࡞੒Մೳ > (1, 2) > ("Hello",
5) > (1, 2.5, [1..3])

Ϧετ͔ΒλϓϧΛ࡞Δ w [JQͰͭͷϦετ͔Βཁૉͷλϓϧ͕࡞੒Մೳ w ௕͞͸୹͍ํʹ߹ΘͤΒΕΔ > zip [1..5] ['a'..'z'] [(1,'a'),(2,'b'),(3,'c'),(4,'d'),(5,'e')]

ϥϜμࣜͰλϓϧΛड͚औΔ w λϓϧ͸Ҿ਺ʹऔΔͱ͖ʹύλʔϯϚονͰ෼ղՄೳ w Ͱ΋͜ͷ৔߹͸[JQ8JUIͨ͠΄͏͕؆ܿ > map (\ (x, y)
-> x + y) $ zip [1..10] [1..10] [2,4,6,8,10,12,14,16,18,20] > zipWith (+) [1..10] [1..10] [2,4,6,8,10,12,14,16,18,20]

͜͜·Ͱͷ·ͱΊ w ෳ਺ͷ஋ͷ૊͕λϓϧ w [JQͰϦετ͔Βλϓϧ͕࡞ΕΔ w ϥϜμࣜͰλϓϧΛҾ਺ʹऔΔʹ͸ύλʔϯϚονΛ࢖͏ w ৔߹ʹΑͬͯ͸[JQ8JUIͰָΛ͠Α͏

࿅श໰୊

࿅श໰୊ w ͔Β·Ͱͷࣗવ਺ͷ͏ͪɺۮ਺ͷ࿨Λܭࢉ͠Α͏ w ώϯτʣ w ۮ਺͔Ͳ͏͔͸FWFOؔ਺Ͱ൑ఆ w ʹͳΕ͹ਖ਼ղ

࿅श໰୊ w ະຬͷ਺Ͱɺ͔ͷഒ਺ʹͳ͍ͬͯΔ਺ͷ߹ܭΛٻΊΑ͏ w 1SPKFDU&VMFS1SPCMFNΑΓ w ͕ग़Ε͹ਖ਼ղ

࿅श໰୊ w ࠷ॳͷݸͷࣗવ਺ʹ͓͚Δೋ৐࿨͸ w ࠷ॳͷݸͷࣗવ਺ʹ͓͚Δ࿨ͷೋ৐͸ w ͜ΕΒͷࠩ͸ w ಉ༷ʹɺ࠷ॳͷݸͷࣗવ਺ʹ͓͚Δೋ৐࿨ͱ࿨ͷೋ৐ͷࠩΛٻΊΑ͏
w 1SPKFDU&VMFS1SPCMFNΑΓ 12 + 22 + ⋯ + 102 = 385 (1 + 2 + ⋯ + 10)2 = 3025 3025 − 385 = 2640

͓ΘΓʹ

͓ΘΓʹ w ͪΐͬͱ͚ͩͰ΋)BTLFMMָ͠Ί·͔ͨ͠ʁ w ΋ͬͱ஌Γͨ͘ͳͬͨΒʮ͍͢͝)BTLFMMͨͷֶ͘͠΅͏ʯΛͥͻ w ͪΐͬͱهड़͕ݹ͍Օॴ͕͋ΔͷͰɺͪ͜Βͷهࣄ΋Ͳ͏ͧ w ೥ʹʮ͍͢͝)BTLFMMͨͷֶ͘͠΅͏ʯΛಡΉ w
IUUQTHPPHMILK&$S

Haskell入門ハンズオン

Haskell入門ハンズオン

More Decks by Aruneko

Other Decks in Programming

Featured

Transcript