lagenorhynque

// コンパイルできる
flix> def applyTwice(f: a -> a, x: a, y: a): (a, a) = (f(x), f(y))
Ok.
// コンパイルできない: 関数 needsRankN は a について多相だが、引数 f は単相である(そして多相にする手段が現状ない)ため
flix> def needsRankN(f: a -> a): (Int32, String) = (f(1), f("hello"))
-- Type Error [E7796] ------------------------------------------------------- $3

>> Unexpected type: expected 'Int32 -> a', found 'a -> a'.

1 | def needsRankN(f: a -> a): (Int32, String) = (f(1), f("hello"))

lagenorhynque

flix> let {name | _} = {name = "Peter", age = 58}; name
Peter
flix> (p -> p#name)({name = "Peter", age = 58})
Peter
flix> ((p: {name = String | _}) -> p#name)({name = "Peter", age = 58})
-- Type Error [E7796] ------------------------------------------- __SHELL__.flix

>> Unexpected type: expected '{ age = Int32, name = String } -> String', found '{ name = String | _ } -> String'.

2 | def _f() = { println(((p: {name = String | _}) -> p#name)({name = "Peter", age = 58})) };

lagenorhynque

slides:
  charset: utf-8
  theme: night
  highlight_theme: monokai-sublime
  separator_vertical: ^\s*----\s*$
revealjs:
  transition: convex
plugins:
  - extra_css:
    - https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css

lagenorhynque

// expressions as a type class
trait Expr[repr: Type -> Type] {
    pub def int(n: Int32): repr[Int32]
    pub def bool(b: Bool): repr[Bool]
    pub def add(e1: repr[Int32], e2: repr[Int32]): repr[Int32]
    pub def mul(e1: repr[Int32], e2: repr[Int32]): repr[Int32]
    pub def eq(e1: repr[a], e2: repr[a]): repr[Bool] with Eq[a]
}

// an evaluator

lagenorhynque

enum Person({ name = String, age = Int32 })

instance ToString[Person] {
    pub def toString(p: Person): String = match p {
        case Person.Person({ name, age }) =>
            "Person(name = ${name}, age = ${age})"
    }
}

def example(): Unit \ IO =

lagenorhynque

slides:
  charset: utf-8
  theme: night
  highlight_theme: monokai-sublime
  separator_vertical: ^\s*----\s*$
revealjs:
  transition: convex
plugins:
  - extra_css:
    - https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css

lagenorhynque

use Sys.Process

// The main entry point.
def main(): Unit \ {Process, Abort, IO} =
    println("Hello World!");

    let n = 5;
    println("The square of ${n} is ${square(n)}.");

    runProcess()

lagenorhynque

slides:
  charset: utf-8
  theme: night
  highlight_theme: monokai-sublime
  separator_vertical: ^\s*----\s*$
revealjs:
  transition: convex
plugins:
  - extra_css:
    - https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css

lagenorhynque

lagenorhynque

Kotlinでミニマルな

Result実装による

関数型エラーハンドリング

#KotlinFest_SSK

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