#Programming_paradigms : #Array_programming (also vector or multidimensional)
Generalizes operations on scalars to apply transparently to vectors, matrices, and higher-dimensional arrays.
Is used in scientific and engineering settings.
e.g. APL, J, Fortran, #Ada, #MATLAB, #Perl Data Language (PDL) and the NumPy extension to #Python.
Vectorized operation
Operations applied at once to an entire set of values like arrays; regardless of whether it is executed on a vector processor or not.
Function rank
Analogous to tensor rank in mathematics
Functions that operate on data may be classified by the number of dimensions they act on.
• Ordinary multiplication, for example, is a scalar ranked function because it operates on zero-dimensional data (individual numbers).
• The cross product operation is an example of a vector rank function because it operates on vectors, not scalars.
• Matrix multiplication is an example of a 2-rank function, because it operates on 2-dimensional objects (matrices).
Collapse operators reduce the dimensionality of an input data array by one or more dimensions. For example, summing over elements collapses the input array by 1 dimension.
Generalizes operations on scalars to apply transparently to vectors, matrices, and higher-dimensional arrays.
Is used in scientific and engineering settings.
e.g. APL, J, Fortran, #Ada, #MATLAB, #Perl Data Language (PDL) and the NumPy extension to #Python.
Vectorized operation
Operations applied at once to an entire set of values like arrays; regardless of whether it is executed on a vector processor or not.
Function rank
Analogous to tensor rank in mathematics
Functions that operate on data may be classified by the number of dimensions they act on.
• Ordinary multiplication, for example, is a scalar ranked function because it operates on zero-dimensional data (individual numbers).
• The cross product operation is an example of a vector rank function because it operates on vectors, not scalars.
• Matrix multiplication is an example of a 2-rank function, because it operates on 2-dimensional objects (matrices).
Collapse operators reduce the dimensionality of an input data array by one or more dimensions. For example, summing over elements collapses the input array by 1 dimension.
The diamond problem
- is an ambiguity that arises when two classes B and C inherit from A, and class D inherits from both B and C. If there is a method in A that B and C have overridden, and D does not override it, then which version of the method does D inherit: that of B, or that of C?
For example, in the context of GUI software development, a class Button may inherit from both classes Rectangle (for appearance) and Clickable (for functionality/input handling), and classes Rectangle and Clickable both inherit from the Object class. Now if the equals method is called for a Button object and there is no such method in the Button class but there is an overridden equals method in Rectangle or Clickable (or both), which method should be eventually called?
How different languages deal with it:
• Common #Lisp: by order "...in the order in which parent classes are named in the subclass definition"
• Curl: "and the secondary constructor will be invoked for all other subclasses."
• Eiffel: "Eiffel will automatically join features together, if they have the same name and implementation."
• Go: compile-time error
• #Java: compile-time error
• #OCaml: by order "...are inherited in the same order, with each newly inherited method overriding any existing methods."
• #Perl: by order "...from as an ordered list. The compiler uses the first method it finds..."
• #Python: by order
• #Ruby: by order "...as rightmost depth first resolution."
• #Scala: by order "allows multiple instantiation of traits, which allows for multiple inheritance by adding a distinction between the class hierarchy and the trait hierarchy. A class can only inherit from a single class, but can mix-in as many traits as desired." This approach is the most similar to #Nile's; traits being qualifications.
• Tcl: by order "the order of specification in the class declaration affects the name resolution for members..."
Languages that allow only single inheritance, where a class can only derive from one base class, do not have the diamond problem.
Moreover, languages such as #Ada, Objective-C, #CSharp, #Delphi/Free #Pascal, Java, #Swift and PHP allow multiple-inheritance of interfaces (called protocols in Objective-C and Swift). Interfaces are like abstract base classes that specify method signatures without implementing any behavior.
When several interfaces declare the same method signature, as soon as that method is implemented (defined) anywhere in the inheritance chain, it overrides any implementation of that method in the chain above it (in its superclasses). Hence, at any given level in the inheritance chain, there can be at most one implementation of any method. Thus, single-inheritance method implementation does not exhibit the Diamond Problem even with multiple-inheritance of interfaces.
- is an ambiguity that arises when two classes B and C inherit from A, and class D inherits from both B and C. If there is a method in A that B and C have overridden, and D does not override it, then which version of the method does D inherit: that of B, or that of C?
For example, in the context of GUI software development, a class Button may inherit from both classes Rectangle (for appearance) and Clickable (for functionality/input handling), and classes Rectangle and Clickable both inherit from the Object class. Now if the equals method is called for a Button object and there is no such method in the Button class but there is an overridden equals method in Rectangle or Clickable (or both), which method should be eventually called?
How different languages deal with it:
• Common #Lisp: by order "...in the order in which parent classes are named in the subclass definition"
• Curl: "and the secondary constructor will be invoked for all other subclasses."
• Eiffel: "Eiffel will automatically join features together, if they have the same name and implementation."
• Go: compile-time error
• #Java: compile-time error
• #OCaml: by order "...are inherited in the same order, with each newly inherited method overriding any existing methods."
• #Perl: by order "...from as an ordered list. The compiler uses the first method it finds..."
• #Python: by order
• #Ruby: by order "...as rightmost depth first resolution."
• #Scala: by order "allows multiple instantiation of traits, which allows for multiple inheritance by adding a distinction between the class hierarchy and the trait hierarchy. A class can only inherit from a single class, but can mix-in as many traits as desired." This approach is the most similar to #Nile's; traits being qualifications.
• Tcl: by order "the order of specification in the class declaration affects the name resolution for members..."
Languages that allow only single inheritance, where a class can only derive from one base class, do not have the diamond problem.
Moreover, languages such as #Ada, Objective-C, #CSharp, #Delphi/Free #Pascal, Java, #Swift and PHP allow multiple-inheritance of interfaces (called protocols in Objective-C and Swift). Interfaces are like abstract base classes that specify method signatures without implementing any behavior.
When several interfaces declare the same method signature, as soon as that method is implemented (defined) anywhere in the inheritance chain, it overrides any implementation of that method in the chain above it (in its superclasses). Hence, at any given level in the inheritance chain, there can be at most one implementation of any method. Thus, single-inheritance method implementation does not exhibit the Diamond Problem even with multiple-inheritance of interfaces.
System software versus application software
System software is designed to operate and control the hardware, and to provide a platform for running application software; e.g. operating systems, utility software, device drivers, compilers, and linkers.
System programming languages, in contrast with application languages, typically offer more direct access to the physical hardware of the machine: an archetypical system programming language in this sense was BCPL.
System programming languages often lack built-in input/output (I/O) facilities because a system-software project usually develops its own I/O mechanisms or builds on top of basic monitor I/O or screen management facilities.
e.g. PL/I, #C, C++, #Ada, #D, Nim, #Rust, #Swift
System software is designed to operate and control the hardware, and to provide a platform for running application software; e.g. operating systems, utility software, device drivers, compilers, and linkers.
System programming languages, in contrast with application languages, typically offer more direct access to the physical hardware of the machine: an archetypical system programming language in this sense was BCPL.
System programming languages often lack built-in input/output (I/O) facilities because a system-software project usually develops its own I/O mechanisms or builds on top of basic monitor I/O or screen management facilities.
e.g. PL/I, #C, C++, #Ada, #D, Nim, #Rust, #Swift