Kazuki-Kachi

// scalaは言わずものかな
val f:Int => Int = args.headOption match {
    case Some(value) => x => + catching(classOf[NumberFormatException]).opt(value.toInt).getOrElse(0)
    case None => x => x
}

    // そもそも宣言で型がわかっているので
val f1:Int => Int = args.headOption match {
    case Some(value) => _ + catching(classOf[NumberFormatException]).opt(value.toInt).getOrElse(0)
    case None => _

Kazuki-Kachi

Dim i As Integer
' それVBならBuildできますよ？
Dim f As Func(Of Integer, Integer) = If(args.Any() AndAlso Integer.TryParse(args.First(), i), Function(x) x + i, Function(x) x)
' 左に型を明記する必要すらない
Dim f1 = If(args.Any() AndAlso Integer.TryParse(args.First(), i), Function(x As Integer) x + i, Function(x As Integer) x)

Kazuki-Kachi

// Type of conditional expression cannot be determined because there is no implicit conversion between 'lambda expression' and 'lambda expression'
Func<int, int> f = args.Any() && int.TryParse(args.First(), out var i) ? x => x + i : x => x;
// 型を書いても無駄
Func<int, int> f1 = args.Any() && int.TryParse(args.First(), out var i) ? (int x) => x + i : (int x) => x;
// OK : args.Any() && int.TryParse(args.First(), out var j) ? (Func<int, int>)(x => x + j) : x => x の型が `Func<int, int>` に確定するので
Func<int, int> f2 = args.Any() && int.TryParse(args.First(), out var j) ? (Func<int, int>)(x => x + j) : x => x;
var f3 = args.Any() && int.TryParse(args.First(), out var k) ? (Func<int, int>)(x => x + k) : x => x;
// OK : この'lambda expression'と `Func<int, int>` との間には implicit conversion が成立する
Func<int, int> f4 = x => x + (args.Any() && int.TryParse(args.First(), out var arg) ? arg : 0);

Kazuki-Kachi

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Sample
{
    class Entity
    {

Kazuki-Kachi

using System.Text;

namespace ConsoleApplication
{
    class Program
    {
        interface IHoge<out T>
        {
            T Foo();
        }