Scala: Passing one implicit parameter implicitly and the other explicitly. Is it possible?
All I can add is: def foo(implicit a: Int, b: String) = println(a, b) implicit val i1 = 1 implicit val s = “” val i2 = 2 foo(i2, implicitly[String])
implicit
Is it possible to plot implicit equations?
I don’t believe there’s very good support for this, but you could try something like import matplotlib.pyplot from numpy import arange from numpy import meshgrid delta = 0.025 xrange = arange(-5.0, 20.0, delta) yrange = arange(-5.0, 20.0, delta) X, Y = meshgrid(xrange,yrange) # F is one side of the equation, G is the other F … Read more
How to declare traits as taking implicit “constructor parameters”?
Actually, I’ve wanted this quite often before, but just came up with this idea. You can translate trait T(implicit impl: ClassName) { def foo = … // using impl here } to [EDITED: original version didn’t provide access to implicit for other methods] trait T { // no need to ever use it outside T … Read more
Unexpected implicit resolution based on inference from return type
1) After rewriting your code as follows: case class Monoid[A](m0: A) // We only care about the zero here implicit def s[T] : Monoid[Set[T]] = Monoid(Set.empty[T]) implicit def l[T] : Monoid[List[T]] = Monoid(List.empty[T]) def mzero[A]()(implicit m: Monoid[A]) : A = m.m0 val zero = mzero[List[Int]]() val zero2: List[Int] = mzero() then becomes clearly why that … Read more
ReSharper and var [duplicate]
Resharper is primarily concerned with helping you refactor code, and the var keyword generally makes refactoring easier. For example, if the return values of any of those functions ever change to a compatibile type, you don’t have to change any of this code. It’s therefore now a little easier to refactor your tabCaseNotes type, for … Read more
What are type classes in Scala useful for?
One use case, as requested… Imagine you have a list of things, could be integers, floating point numbers, matrices, strings, waveforms, etc. Given this list, you want to add the contents. One way to do this would be to have some Addable trait that must be inherited by every single type that can be added … Read more
TypeError: Can’t convert ‘int’ object to str implicitly [duplicate]
You cannot concatenate a string with an int. You would need to convert your int to a string using the str function, or use formatting to format your output. Change: – print(“Ok. Your balance is now at ” + balanceAfterStrength + ” skill points.”) to: – print(“Ok. Your balance is now at {} skill points.”.format(balanceAfterStrength)) … Read more
Good example of implicit parameter in Scala? [closed]
In a sense, yes, implicits represent global state. However, they are not mutable, which is the true problem with global variables — you don’t see people complaining about global constants, do you? In fact, coding standards usually dictate that you transform any constants in your code into constants or enums, which are usually global. Note … Read more
Android, How to read QR code in my application?
try { Intent intent = new Intent(“com.google.zxing.client.android.SCAN”); intent.putExtra(“SCAN_MODE”, “QR_CODE_MODE”); // “PRODUCT_MODE for bar codes startActivityForResult(intent, 0); } catch (Exception e) { Uri marketUri = Uri.parse(“market://details?id=com.google.zxing.client.android”); Intent marketIntent = new Intent(Intent.ACTION_VIEW,marketUri); startActivity(marketIntent); } and in onActivityResult(): @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == 0) { if (resultCode … Read more
explicit and implicit c#
The implicit and explicit keywords in C# are used when declaring conversion operators. Let’s say that you have the following class: public class Role { public string Name { get; set; } } If you want to create a new Role and assign a Name to it, you will typically do it like this: Role … Read more