Nullary constructor
In computer programming, a nullary constructor is a constructor that takes no arguments. Also known as a 0-argument constructor or no-argument constructors.
Object-oriented constructors
In object-oriented programming, a constructor is code that is run when an object is created. Default constructors of objects are usually nullary.
Java example
public class Example
{
protected int data;
/* Nullary constructor */
public Example()
{
this(0);
}
/* Non-nullary constructor */
public Example(final int data)
{
this.data = data;
}
}
Algebraic data types
In algebraic data types, a constructor is one of many tags that wrap data. If a constructor does not take any data arguments, it is nullary.
Haskell example
-- nullary type constructor with two nullary data constructors
data Bool = False
| True
-- non-nullary type constructor with one non-nullary data constructor
data Point a = Point a a
-- non-nullary type constructor with...
data Maybe a = Nothing -- ...nullary data constructor
| Just a -- ...unary data constructor
gollark: Oookay.
gollark: Wait, how would you know about stupidly expensive FTL travel for thousands of years before you had even figured out what the speed of light was?
gollark: There may also be different stuff produced in each system, or at least some stuff produced more cheaply in some.
gollark: I don't think anyone knows the answer to that.
gollark: … that would do it, why did I never think of that... but you still need room for the ship component stuff.
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