N things Scala should steal from other languages

Chris Birchall

Methodology

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GOTO keyword

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Cheeky control structure

php, BASIC

0/5

https://xkcd.com/292/

SAMPLE

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Better type inference

(credit: Julien Truffaut)

Haskell, ML

4/5

3/5

@ List(1,2,3).foldLeft(Nil){ (xs, x) => x::xs }
type mismatch;
 found   : List[Int]
 required: scala.collection.immutable.Nil.type

Paul Chiusano's blog; Dotty and types: the story so far; Colored Local Type Inference; OutsideIn(X); Extending Hindley-Milner Type Inference with Coercive Structural Subtyping; Scala contributors thread

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Row types

(credit: Mark Eibes)

PureScript

2/5

1/5

Unordered, labelled collection of types.

Can be used for extensible effects.

Using Purescript's Row Types for Tracking Validations; PureScript Eff documentation

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Typed holes

Agda, Haskell, Idris

5/5 (Done!)

0/5

cb372/scala-typed-holes

Leave deliberate 'holes' in your program, for interactive type-driven development

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Dependent types

Idris

1/5

0/5

Types can depend on values

e.g. "List of Ints with size 4"

Idris documentation; Oskar Wickström's talk on Finite State Machines

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Linear/affine/quant types

Idris 2, Linear Haskell, ATS, Rust

1/5

0/5

The Pain Of Real Linear Types in Rust; Edwin Brady's Idris 2 talk at CodeMesh; SPJ's talk on Linear Haskell; deech's Strange Loop talk on ATS

Can't use a value more than once, must use a value at least once, etc.

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Reference capabilities

Pony

1/5

0/5

Pony documentation

Safe sharing of mutable state

(credit: 𝖬𝖺𝗋𝖼𝗈 𝖡𝗈𝗋𝗌𝗍)

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Fast compiler

Java, Go

3/5

2/5

Nobody ever needing to embed that xkcd comic in their slides again

(credit: Channing Walton)

On Kentucky Mule; Reasonable Scala Compiler

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Tail-call optimisation

2/5

0/5

Stack-safety without sacrificing heap.

Requires a JVM change.

Tail calls in F#

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Coroutines

Go, Lua, Kotlin, ES6 (generators)

5/5 (Done!)

0/5

Lightweight threads with user-defined suspension points

Coroutines library; First-class Coroutines for Scala; Diving deep into Kotlin Coroutines; Project Loom (thanks to Diego for the tip!)

(credit: Maksim Aleshko)

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Type providers

F#, Idris

3/5

0/5

Generating new types based on external input, e.g. a schema file

Idris documentation; F# documentation; F# type provider demo by Tomas Patricek; Macro-supported DSLs for schema bindings

(credit: Jan Schulte)

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Hoogle

Haskell

3/5 (would be nice if Scaladex had an API...)

0/5

Search for functions by name or type signature

Hoogle

(credit: Debasish Ghosh, Diogo Castro)

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Deriving

Haskell

3/5

5/5 (see Martin's keynote!)

Automatic derivation of type class instances

scalaz-deriving; kittens

(credit: Martin Lechner)

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WebAssembly

Rust

4/5

0/5

The future of the web!

Serverless Rust with AWS Lambda and WebAssembly

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First-class purity

Haskell, PureScript, Eff

4/5

3/5

Pure/impure separation enforced by the type system.

Effect system built in to the language.