sclib - simple scala utility library

stdlib extensions
toolbox to work with files and directories
utilities
zero runtime dependencies
jvm and scala.js bits
scaladoc

quick start

the library are published to bintray for scala 2.10 and 2.11. add the following snippet to your build.sbt file:

- for the jvm:

    resolvers += Resolver.bintrayRepo("j-keck", "maven")
    libraryDependencies += "net.jkeck" %% "sclib" % "0.6"

for scala.js

  resolvers += Resolver.bintrayRepo("j-keck", "maven")
  libraryDependencies += "net.jkeck" %%% "sclib" % "0.6"

content

stdlib extensions
- Either
- Try
- Option
- List
- String
- Java8 interoperability
io
util
patterns
(very) simple serialize / deserialize

stdlib extensions

utilities for the scala stdlib.

to import all in one use import sclib.ops.all._

Either

scaladoc

import sclib.ops.either._

shorthand Left / Right constructor:

scala> "a string".left
res0: Either[String,Nothing] = Left(a string)

scala> "a string".left[Int] 
res1: Either[String,Int] = Left(a string)

scala> 4.right[String]
res2: Either[String,Int] = Right(4)

sequence on Traversable[Either[A, B]] to reducing many Eithers into a single Either

scala> List(3.right, 4.right).sequence
res3: Either[Nothing,List[Int]] = Right(List(3, 4))

scala> List(3.right, 4.right, "BOOM".left).sequence
res4: Either[String,List[Int]] = Left(BOOM)

scala> Vector(2.right, 5.right).sequence
res5: Either[Nothing,scala.collection.immutable.Vector[Int]] = Right(Vector(2, 5))

right biased either

scala> for {
     |   a <- Right(1)
     |   b <- Right(4)
     | } yield a + b
res6: Either[Nothing,Int] = Right(5)

Try

scaladoc

import sclib.ops.`try`._

shorthand constructor for Success

scala> 3.success
res0: scala.util.Try[Int] = Success(3)

shorthand constructor for Failure from a Throwable

scala> new IllegalArgumentException("BOOM").failure[Int]
res1: scala.util.Try[Int] = Failure(java.lang.IllegalArgumentException: BOOM)

shorthand constructor for Failure from a String

scala> "BOOM".failure
res2: scala.util.Try[Nothing] = Failure(java.lang.Exception: BOOM)

sequence on Traversable[Try[A]] to reducing many Trys into a single Try

scala> List(3.success, 44.success).sequence
res3: scala.util.Try[List[Int]] = Success(List(3, 44))

scala> List(3.success, "BOOM".failure, 44.success).sequence
res4: scala.util.Try[List[Int]] = Failure(java.lang.Exception: BOOM)

scala> Vector(1.success, 2.success).sequence
res5: scala.util.Try[scala.collection.immutable.Vector[Int]] = Success(Vector(1, 2))

Option

scaladoc

import sclib.ops.option._

shorthand constructor for Some (with type Option[A])

scala> 123.some
res0: Option[Int] = Some(123)

shorthand constructor for None (with type Option[A])

scala> none
res1: Option[Nothing] = None

scala> none[String]
res2: Option[String] = None

sequence on Traversable[Option[A]] to reducing many Options into a single Option

scala> List(3.some, 44.some).sequence
res3: Option[List[Int]] = Some(List(3, 44))

scala> List(3.some, none, 44.some).sequence
res4: Option[List[Int]] = None

scala> Vector(1.some, 2.some).sequence
res5: Option[scala.collection.immutable.Vector[Int]] = Some(Vector(1, 2))

List

scaladoc

import sclib.ops.list._

unfoldLeft / unfoldRight

scala> ListOps.unfoldRight(0){ i =>
     |   if(i > 10) None else Some((i, i + 1))
     | }
res0: List[Int] = List(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

partition a list into sub-lists - start by the given predicate

scala> val l = List("-- heading1", "a", "b", "-- heading2", "c", "d")
l: List[String] = List(-- heading1, a, b, -- heading2, c, d)

scala> l.partitionsBy(_.startsWith("--"))
res1: List[List[String]] = List(List(-- heading1, a, b), List(-- heading2, c, d))

String

scaladoc

import sclib.ops.string._

save / easy to compose parser for Int, Long, Double, Char, Boolean and Date. the result can be wrapped in a Try, Option, Either[String, ?] or Either[Throwable, ?].

scala> import scala.util.Try
import scala.util.Try

scala> "123".parseInt[Try]
res0: scala.util.Try[Int] = Success(123)

scala> "one".parseInt[Try]
res1: scala.util.Try[Int] = Failure(java.lang.NumberFormatException: For input string: "one")

scala> "123".parseInt[Option]
res2: Option[Int] = Some(123)

scala> "one".parseInt[Option]
res3: Option[Int] = None

scala> "123".parseInt[Either[String, ?]]
res4: scala.util.Either[String,Int] = Right(123)

scala> "one".parseInt[Either[String, ?]]
res5: scala.util.Either[String,Int] = Left(java.lang.NumberFormatException: For input string: "one")

scala> import sclib.ops.either._
import sclib.ops.either._

scala> for{
     |  a <- "123".parseInt[Try]
     |  b <- "44".parseInt[Try]
     | } yield a + b
res6: scala.util.Try[Int] = Success(167)

scala> for{
     |  a <- "one".parseInt[Try]
     |  b <- "44".parseInt[Try]
     | } yield a + b
res7: scala.util.Try[Int] = Failure(java.lang.NumberFormatException: For input string: "one")

parseDate[F[_]](pattern: String)

scala> "Feb 01 16:30:10 2020".parseDate[Try]("MMM DD HH:mm:ss yyyy")
res8: scala.util.Try[java.util.Date] = Success(Wed Jan 01 16:30:10 CET 2020)

parseDate[F[_]] which expects a implicit SimpleDateFormat in scope

implicit val sdf = new java.text.SimpleDateFormat("DD.MM.yyyy HH:mm:ss")

scala> "01.02.2020 16:30:10".parseDate[Try]
res9: scala.util.Try[java.util.Date] = Success(Wed Jan 01 16:30:10 CET 2020)

java8 interoperability

scaladoc

import sclib.ops.java8._

convert a java.util.stream.Stream to 'scala.collection.Iterator'

scala> java.util.stream.Stream.of(1, 2, 3, 4).toIterator
res0: Iterator[Int] = non-empty iterator

convert a java.util.stream.Stream to 'scala.collection.immutable.List'

scala> java.util.stream.Stream.of(1, 2, 3, 4).toList
res1: List[Int] = List(1, 2, 3, 4)

convert a scala.Function1 to a java.util.function.Function

scala> java.util.stream.Stream.of(1, 2, 3,4).map((_: Int) * 10).toArray
res2: Array[Object] = Array(10, 20, 30, 40)

convert a scala.Function1 to a java.util.function.Predicate

scala> java.util.stream.Stream.of(1, 2, 3, 4).filter((_: Int) < 3).toArray
res3: Array[Object] = Array(1, 2)

convert a scala.Function1 to a java.util.function.Consumer

scala> java.util.stream.Stream.of(1, 2, 3, 4).forEach(println(_: Int))
1
2
3
4

convert a scala.Function2 to a java.util.function.BinaryOperator

scala> java.util.stream.Stream.of(1, 2, 3).reduce(0, (_: Int) + (_: Int))
res5: Int = 6

io

scaladoc

simple version of java's 'try-with-resource'

import sclib.io.autoClose
import java.nio.file.Paths
import java.nio.file.StandardOpenOption.{CREATE, WRITE}
import java.nio.channels.FileChannel
for {
  in <- autoClose(FileChannel.open(Paths.get("/tmp/input")))
  out <- autoClose(FileChannel.open(Paths.get("/tmp/output"), CREATE, WRITE))
} in.transferTo(0, Long.MaxValue, out)
// `in` and `out` are closed here

filesystem

scaladoc

import sclib.io.fs._

functions to work with files and directories.

all functions which can throw a exception are wrapped in a Try.

scala> for {
     |   wd <- dir("sclib-example")
     |   wd <- wd.createTemp              // create a temp work-dir (path is something like: '/tmp/sclib-example6964564891871111476')
     |   fh <- file(wd, "a-file")         // create a file under the work-dir
     |   _ <- fh.append("first line\n")   // write a line
     |   _ <- fh.append("second line")
     |   fs <- fh.size                    // file-size  (fh.size returns Try[Long])
     |   lc <- fh.lines.map(_.length)     // line-count (fh.lines returns Try[Iterator[String]])
     |   wc <- fh.slurp.map(_.size)       // word-count (fh.slurp returns Try[String])
     |   _ <- wd.deleteR                  // delete the work-dir recursive
     | } yield s"file size: ${fs}, line count: ${lc}, word count: ${wc}"
res0: scala.util.Try[String] = Success(file size: 22, line count: 2, word count: 22)

type-class based write, writeLines, append and appendLines functions with instances for basic types

scala> for {
     |   wd <- dir("sclib-example")
     |   wd <- wd.createTemp                                   // create a temp work-dir (path is something like: '/tmp/sclib-example6964564891871111476')
     |   fh <- file(wd, "a-file")                              // create a file under the work-dir
     |   _ <- fh.writeLines("1. apple")                        // string
     |   _ <- fh.appendLines(List("2. banana", "3. cherry"))   // list of string
     |   _ <- fh.append(4)                                     // int
     |   _ <- fh.append('.')                                   // char
     |   _ <- fh.append(Vector(' ', 'd', 'o', 'g'))            // vector of char
     |   content <- fh.slurp                                   // read the whole file 
     |   _ <- wd.deleteR                                       // delete the work-dir recursive
     | } yield content
res1: scala.util.Try[String] =
Success(1. apple
2. banana
3. cherry
4. dog)

net

scaladoc

import sclib.io.net._

download a file

scala> import sclib.io.fs._
scala> for {
     |    url <- url("http://example.com")         // save way to get a 'java.net.URL'
     |    local <- url.fetch(file("example.com"))  // download the url-content
     |    content <- local.slurp                   // read the local copy
     |    _ <- local.delete()                      // delete the local copy
     |  } yield content.take(20)
res0: scala.util.Try[String] = Success(<!doctype html>
      <htm)

util

scaladoc

simple Union type

scala> import sclib.util.union._
import sclib.util.union._

scala> def f[A: (Int Or String)#Check](a: A): Int = a match {
     |   case i: Int => i
     |   case s: String => s.length
     | }
f: [A](a: A)(implicit evidence$1: <:<[sclib.util.union.Contra[sclib.util.union.Contra[A]],sclib.util.union.Contra[sclib.util.union.Contra[Int] with sclib.util.union.Contra[String]]])Int

scala> f(5)
res0: Int = 5

scala> f("hey")
res1: Int = 3

scala> // this throws a compiler error:
     | // f(5L)

"pattern's"

scaladoc

import sclib.patterns._

AppF

simple AppFunction - expect's a function with receives a config and returns a Either

scala> import sclib.ops.either._
import sclib.ops.either._

scala> val action = for {
     |   a <- AppF{i: Int => i.right[String]}
     |   b <- AppF{i: Int => if(i < 5) (i * 10).right else "BOOM".left}
     |   c <- AppF.lift(33.right[String])
     | } yield (a, b, c)
action: sclib.z.EitherT[[β]sclib.z.Reader[Int,β],String,(Int, Int, Int)] = EitherT(Reader(<function1>))

scala> action.runEitherT.runReader(2)
res0: Either[String,(Int, Int, Int)] = Right((2,20,33))

scala> action.runEitherT.runReader(8)
res1: Either[String,(Int, Int, Int)] = Left(BOOM)

(very) simple serialize / deserialize

scaladoc

i use this for little scala.js apps for the client / server communication to keep the resulting '.js' files small.

values are converted to strings and prefixed with their length. so the int value 31593 becomes "5:31593". to deserialize this value, we give the deserializer the expected type, and it parse / converts the given string.

import sclib.serialization.simple._

#####for stdlib

scala> val s = Serialize("a simple string")
s: String = 15:a simple string

scala> Deserialize[String](s)
res0: Either[String,String] = Right(a simple string)

scala> val t = Serialize("a tuple with a string and a list" -> List(4, 23, 1))
t: String = 32:a tuple with a string and a list10:1:42:231:1

scala> Deserialize[(String, List[Int])](t)
res1: Either[String,(String, List[Int])] = Right((a tuple with a string and a list,List(4, 23, 1)))

#####for own types

define your types and the typeclass instances for serialization / deserialization

case class C(a: String, b: List[Int], c: Either[Int, String])

implicit val cSer = new Serialize[C]{
  override def apply(cInst: C): String = {
    import cInst._
    Serialize(a) + Serialize(b) + Serialize(c)
  }
}

implicit val cDes = new Deserialize[C]{
  override def apply: DeserializeState[C] = for {
    a <- Deserialize[String]
    b <- Deserialize[List[Int]]
    c <- Deserialize[Either[Int, String]]
  } yield C(a, b, c)
}

use it

scala> val s = Serialize(C("the string", List(4, 2, 1), Right("i'm ok")))
s: String = 10:the string9:1:41:21:19:R6:i'm ok

scala> Deserialize[C](s)
res4: Either[String,C] = Right(C(the string,List(4, 2, 1),Right(i'm ok)))

j-keck / sclib 0.6

sclib - simple scala utility library

quick start

content

stdlib extensions

Either

Try

Option

List

String

java8 interoperability

io

filesystem

net

util

"pattern's"

AppF

(very) simple serialize / deserialize

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Contributors

4 Dependencies

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