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99 lines
2.7 KiB
Go
99 lines
2.7 KiB
Go
// Copyright (c) 2023 IBM Corp.
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// All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mostlyadequate
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import (
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"fmt"
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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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IOE "github.com/IBM/fp-go/ioeither"
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O "github.com/IBM/fp-go/option"
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P "github.com/IBM/fp-go/predicate"
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S "github.com/IBM/fp-go/string"
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)
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var (
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// httpGet :: Route -> Task Error JSON
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httpGet = F.Flow2(
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S.Format[string]("json for %s"),
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IOE.Of[error, string],
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)
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// routes :: Map Route Route
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routes = map[string]string{
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"/": "/",
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"/about": "/about",
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}
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// validate :: Player -> Either error Player
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validatePlayer = E.FromPredicate(P.ContraMap(Player.getName)(S.IsNonEmpty), F.Flow2(Player.getId, errors.OnSome[int]("player %d must have a name")))
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// readfile :: String -> String -> Task Error String
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readfile = F.Curry2(func(encoding, file string) IOE.IOEither[error, string] {
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return IOE.Of[error](fmt.Sprintf("content of %s (%s)", file, encoding))
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})
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// readdir :: String -> Task Error [String]
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readdir = IOE.Of[error](A.From("file1", "file2", "file3"))
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)
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func Example_solution12A() {
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// getJsons :: Map Route Route -> Task Error (Map Route JSON)
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getJsons := IOE.TraverseRecord[string](httpGet)
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fmt.Println(getJsons(routes)())
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// Output:
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// Right[<nil>, map[string]string](map[/:json for / /about:json for /about])
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}
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func Example_solution12B() {
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// startGame :: [Player] -> [Either Error String]
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startGame := F.Flow2(
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E.TraverseArray(validatePlayer),
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E.MapTo[error, []Player]("Game started"),
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)
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fmt.Println(startGame(A.From(playerAlbert, playerTheresa)))
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fmt.Println(startGame(A.From(playerAlbert, Player{Id: 4})))
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// Output:
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// Right[<nil>, string](Game started)
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// Left[*errors.errorString, string](player 4 must have a name)
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}
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func Example_solution12C() {
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traverseO := O.Traverse[string](
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IOE.Of[error, O.Option[string]],
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IOE.Map[error, string, O.Option[string]],
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)
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// readFirst :: String -> Task Error (Maybe String)
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readFirst := F.Pipe2(
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readdir,
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IOE.Map[error](A.Head[string]),
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IOE.Chain(traverseO(readfile("utf-8"))),
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)
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fmt.Println(readFirst())
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// Output:
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// Right[<nil>, option.Option[string]](Some[string](content of file1 (utf-8)))
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}
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