mirror of
https://github.com/IBM/fp-go.git
synced 2025-08-10 22:31:32 +02:00
fix: add more examples
Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>
This commit is contained in:
Dr. Carsten Leue
@@ -19,9 +19,12 @@ import (
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"fmt"
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"time"
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A "github.com/IBM/fp-go/array"
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E "github.com/IBM/fp-go/either"
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"github.com/IBM/fp-go/errors"
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F "github.com/IBM/fp-go/function"
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I "github.com/IBM/fp-go/identity"
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IOE "github.com/IBM/fp-go/ioeither"
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N "github.com/IBM/fp-go/number"
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O "github.com/IBM/fp-go/option"
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"github.com/IBM/fp-go/ord"
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@@ -40,6 +43,45 @@ func getBalance(a Account) float32 {
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return a.Balance
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}
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type (
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Chapter08User struct {
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Id int
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Name string
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Active bool
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Saved bool
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}
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)
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var (
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albert08 = Chapter08User{
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Id: 1,
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Active: true,
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Name: "Albert",
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}
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gary08 = Chapter08User{
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Id: 2,
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Active: false,
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Name: "Gary",
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}
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theresa08 = Chapter08User{
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Id: 3,
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Active: true,
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Name: "Theresa",
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}
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yi08 = Chapter08User{Id: 4, Name: "Yi", Active: true}
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)
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func (u Chapter08User) getName() string {
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return u.Name
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}
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func (u Chapter08User) isActive() bool {
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return u.Active
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}
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var (
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ordFloat32 = ord.FromStrictCompare[float32]()
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UpdateLedger = F.Identity[Account]
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@@ -55,6 +97,33 @@ var (
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Withdraw(20),
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O.Fold(F.Constant("You're broke!"), FinishTransaction),
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)
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// showWelcome :: User -> String
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showWelcome = F.Flow2(
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Chapter08User.getName,
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S.Format[string]("Welcome %s"),
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)
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// checkActive :: User -> Either error User
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checkActive = E.FromPredicate(Chapter08User.isActive, F.Constant1[Chapter08User](fmt.Errorf("Your account is not active")))
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// validateUser :: (User -> Either String ()) -> User -> Either String User
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validateUser = F.Curry2(func(validate func(Chapter08User) E.Either[error, any], user Chapter08User) E.Either[error, Chapter08User] {
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return F.Pipe2(
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user,
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validate,
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E.MapTo[error, any](user),
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)
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})
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// save :: User -> IOEither error User
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save = func(user Chapter08User) IOE.IOEither[error, Chapter08User] {
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return IOE.FromIO[error](func() Chapter08User {
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var u = user
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u.Saved = true
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return u
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})
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}
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)
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func Withdraw(amount float32) func(account Account) O.Option[Account] {
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@@ -131,3 +200,77 @@ func Example_getAge() {
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// Left[*time.ParseError, float64](parsing time "July 4, 2001" as "2006-01-02": cannot parse "July 4, 2001" as "2006")
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// If you survive, you will be 6837
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}
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func Example_solution08A() {
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incrF := I.Map(N.Add(1))
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fmt.Println(incrF(I.Of(2)))
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// Output: 3
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}
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func Example_solution08B() {
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// initial :: User -> Option rune
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initial := F.Flow3(
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Chapter08User.getName,
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S.ToRunes,
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A.Head[rune],
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)
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fmt.Println(initial(albert08))
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// Output:
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// Some[int32](65)
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}
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func Example_solution08C() {
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// eitherWelcome :: User -> Either String String
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eitherWelcome := F.Flow2(
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checkActive,
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E.Map[error](showWelcome),
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)
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fmt.Println(eitherWelcome(gary08))
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fmt.Println(eitherWelcome(theresa08))
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// Output:
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// Left[*errors.errorString, string](Your account is not active)
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// Right[<nil>, string](Welcome Theresa)
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}
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func Example_solution08D() {
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// // validateName :: User -> Either String ()
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validateName := F.Flow3(
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Chapter08User.getName,
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E.FromPredicate(F.Flow2(
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S.Size,
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ord.Gt(ord.FromStrictCompare[int]())(3),
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), errors.OnSome[string]("Your name %s is larger than 3 characters")),
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E.Map[error](F.ToAny[string]),
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)
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saveAndWelcome := F.Flow2(
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save,
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IOE.Map[error](showWelcome),
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)
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register := F.Flow3(
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validateUser(validateName),
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IOE.FromEither[error, Chapter08User],
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IOE.Chain(saveAndWelcome),
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)
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fmt.Println(validateName(gary08))
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fmt.Println(validateName(yi08))
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fmt.Println(register(albert08)())
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fmt.Println(register(yi08)())
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// Output:
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// Right[<nil>, string](Gary)
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// Left[*errors.errorString, <nil>](Your name Yi is larger than 3 characters)
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// Right[<nil>, string](Welcome Albert)
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// Left[*errors.errorString, string](Your name Yi is larger than 3 characters)
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}
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@@ -17,10 +17,13 @@ package mostlyadequate
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import (
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"fmt"
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"path"
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A "github.com/IBM/fp-go/array"
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F "github.com/IBM/fp-go/function"
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"github.com/IBM/fp-go/io"
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O "github.com/IBM/fp-go/option"
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S "github.com/IBM/fp-go/string"
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)
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type (
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@@ -37,20 +40,70 @@ type (
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AddressBook struct {
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Addresses []Address
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}
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Chapter09User struct {
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Id int
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Name string
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Address Address
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}
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)
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func getAddresses(ab AddressBook) []Address {
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var (
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albert09 = Chapter09User{
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Id: 1,
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Name: "Albert",
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Address: Address{
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Street: Street{
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Number: 22,
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Name: "Walnut St",
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},
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},
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}
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gary09 = Chapter09User{
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Id: 2,
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Name: "Gary",
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Address: Address{
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Street: Street{
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Number: 14,
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},
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},
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}
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theresa09 = Chapter09User{
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Id: 3,
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Name: "Theresa",
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}
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)
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func (ab AddressBook) getAddresses() []Address {
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return ab.Addresses
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}
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func getStreet(s Address) Street {
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func (s Address) getStreet() Street {
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return s.Street
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}
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var FirstAddressStreet = F.Flow3(
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getAddresses,
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A.Head[Address],
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O.Map(getStreet),
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func (s Street) getName() string {
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return s.Name
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}
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func (u Chapter09User) getAddress() Address {
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return u.Address
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}
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var (
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FirstAddressStreet = F.Flow3(
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AddressBook.getAddresses,
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A.Head[Address],
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O.Map(Address.getStreet),
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)
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// getFile :: IO String
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getFile = io.Of("/home/mostly-adequate/ch09.md")
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// pureLog :: String -> IO ()
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pureLog = io.Logf[string]("%s")
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)
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func Example_street() {
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@@ -62,3 +115,35 @@ func Example_street() {
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// Output:
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// Some[mostlyadequate.Street]({Mulburry 8402})
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}
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func Example_solution09A() {
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// // getStreetName :: User -> Maybe String
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getStreetName := F.Flow4(
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Chapter09User.getAddress,
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Address.getStreet,
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Street.getName,
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O.FromPredicate(S.IsNonEmpty),
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)
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fmt.Println(getStreetName(albert09))
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fmt.Println(getStreetName(gary09))
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fmt.Println(getStreetName(theresa09))
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// Output:
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// Some[string](Walnut St)
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// None[string]
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// None[string]
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}
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func Example_solution09B() {
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logFilename := F.Flow2(
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io.Map(path.Base),
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io.ChainFirst(pureLog),
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)
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fmt.Println(logFilename(getFile)())
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// Output:
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// ch09.md
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}
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