Is there a language out there in which parameters are placed inside method name?

Question

in JavaScript:

function getTopCustomersOfTheYear(howManyCustomers, whichYear) {
   // Some code here.
}
getTopCustomersOfTheYear(50, 2010);

in C#:

public List<Customer> GetTopCustomersOfTheYear(int howManyCustomers, 
 int whichYear)
{
   // Some code here
}
List<Customer> customers = GetTopCustomersOfTheYear(50, 2010);

in PHP:

public function getTopCustomersOfTheYear($howManyCustomers, $whichYear)
{
   // Some code here
}
$customers = getTopCustomersOfTheYear(50, 2010);

Is there any language out there which support this syntax:

function GetTop(x)CustomersOfTheYear(y)
{
    // Some code here
}
returnValue = GetTop(50)CustomersOfTheYear(2010);

Isn't it more semantic, more readable form of writing a function?

Update: The reason I'm asking this question is that, I'm writing an article about a new syntax for a new language. However, I thought that having such syntax for declaring methods could be nicer and more friendly to developers and would decrease learning-curve of the language, because of being more closer to natural language. I just wanted to know if this feature has already been contemplated upon or not.

Answer 1

Yes, and yes. Yes there's such a language, and yes, many people find it more readable once they get used to it.

In Objective-C, the method would be:

- (NSArray*)getTop:(int)count customersOfTheYear:(Year)year;

That's actually a pretty contrived example that doesn't read very well, so here's a better one from actual code:

+ (UIColor *)colorWithRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue alpha:(CGFloat)alpha;

That the prototype for a method that returns a new UIColor instance using the red, green, blue, and alpha values. You'd call it like this:

UIColor *violet = [UIColor colorWithRed:0.8 green:0.0 blue:0.7 alpha:1.0];

Read more about message names with interspersed parameters in The Objective-C Programming Language.

Answer 2

Objective-C does that. Here is a typical prototype:

- (void) areaWithHeight: (float) height andWidth: (float) width;

Here is how you call such a method:

float area = [self areaWithHeight: 75 andWidth: 20];

Objective-C is primarily used with Cocoa for Mac OS X and Cocoa Touch for iOS, but gcc will build Objective-C code on just about every platform that gcc works on.

Answer 3

Answer: smalltalk

http://en.wikipedia.org/wiki/Smalltalk

'hello world' indexOf: $o startingAt: 6 is like Java's "hello world".indexOfStartingAt(o, 6)

Rectangle width: 100 height: 200 is like Java's new Rectangle(100, 200)

The syntax is... expression word1: parm1 word2: parm2 word3: parm3 ... The name of the method called is the concatenation of all the words.

Answer 4

I believe you are looking for the abstraction called "fluent interface (I am hereby raising a comment, originally made by @Jesper, to an "answer")." This now common pattern has been successfully implemented in many languages, of which Objective-C is only one.

Here is a pretty clean example:

Person bo = new Person();
bo.Set.FirstName("Bo").LastName("Peep").Age(16).Size("Little").LostHerSheep();

You can see how something like this can be implemented in Randy Patterson's How to design a fluent interface.

Andre Vianna gives a brief history and then discusses possible implementations in two more article parts, including plenty of useful information. Vianna points back to the old idea I first encountered in Smalltalk 80 called "cascading," that enabled sending multiple messages to the same object. It looked like this:

aThing one: 'one';
  two: 'two';
  other.

Cascading subsequently evolved into "method chaining," where we "Make modifier methods return the host object, so that multiple modifiers can be invoked in a single expression." Method chaining later grew up to become the fluent interface concept we know and use frequently today. What you plan to do looks very similar.

Ayende Rahien discusses how "fluent interface" may differ significantly enough from "method chaining" to deserve its own name.

Fluent interfaces are commonly seen in some of the new tools used in behavior driven development (BDD) and have even found their way into NUnit, a major .NET unit testing tool, in its new Constraint-Based Assert Model.

These basic approaches have subsequently been implemented in other languages, including Ruby, Python, C#, Objective-C and Java. To implement something similar, you will want to study up on the idea of "closure," which is pretty much fundamental to chaining and fluency.

Perhaps you can improve on these models; that's how we get great new languages. Still, I believe that fully understanding method chaining and fluent interfaces will give you a great starting point from which to evolve your ideas!

Answer 5

In Common lisp, you can define keyword arguments for a function like this:

(defun area (&key width height)
    (* width height))

The function is called like this:

(area :width 2 :height 3)

In Ada you don't need a special declaration - you can call any procedure or function alternatively by listing the arguments in order, or by naming the arguments like this:

a := area(width => 2, height => 3);

Finally, the boost library includes a layer of hacks to add the feature to C++: http://www.boost.org/doc/libs/release/libs/parameter/doc/html/index.html

Answer 6

Python has keyword parameters. Function definition example

def getTopCustomers(count,year):
...

Function call example

x = getTopCustomers(year=1990, count=50)

(I understand this is not be quite in the spirit of the original question, but if keyword parameters in lisp qualifies, so do this. In Smalltalk and Objective-C, however, the keywords between arguments are really part of the function name/lookup.)

Answer 7

I couldn't find the name of it, but there's a design pattern to accomplish something similar, where a function call returns a new object modified as described. For example:

query = db.getTopCustomers(50).forYear(2010);

It isn't used very often because your data has to be very orthogonal in order to avoid unmanageable complexity under the hood, but can be useful in the right circumstances.

Answer 8

In JavaScript or any other language that supports closures, you can curry a function like this:

function getTopCustomersFunc(count) {
    return function(year) {
       // run some query, return count customers from year
    }
}
var top20Func = getTopCustomersFunc(20);
var top20Customers2005 = top20Func(2005);
var top20Customers2008 = top20Func(2008);

Answer 9

While not a programming language per se, Cucumber takes parameters in the middle of function names, which can include spaces and are meant to look like English.

The 'functions' are defined in Ruby however

# definition
Given /^I calculate (.*) times (.*)$/ do |x, y|
    @result = x.to_i * y.to_i
end

Then /^the result should be (.*)$/ do |v|
    @result.should == v.to_i
end

# usage
Scenario:
    Given I calculate 6 times 9
    Then the result should be 42

Answer 10

This depends on your definition of "language", but the robotframework testing framework lets you define keywords this way. From their documentation on embedded arguments:

Select ${animal} from list | Open page | pet selection
                            | Select item from list | animal_list | ${amimal}

The above declares a new keyword (essentially a function) named "select ${animal} from list" where '${animal}' is a parameter. You call it like "select cat from list"

Answer 11

Inform 7.

To create (employee - a person) being paid (salary - a number):
    say "Welcome to your new job, [name of employee]!";
    choose a blank row from the table of employees;
    now the paid entry is the salary;
    now the name entry is the name of the employee.

And so on.