Why isn't it a common practice for languages to have method arguments passed inside method names?

Question

Why is not it a common practice for languages to have method arguments passed inside method names?

For instance, wouldn't something like: shop.Sell(15)Notebooks (although looking pretty unusual) be more readable than shop.SellNotebooks(15)?

Also, this could simplify fluent APIs: instead of implementing additional interfaces for things like money.Add(20).Dollars() we could simply use methods: money.Add(20)Dollars and so on.

Answer 1

For instance, wouldn't something like: shop.Sell(15)Notebooks (although looking pretty unusual) be more readable than shop.SellNotebooks(15)?

No, it wouldn't.

Programmers don't read code as English; they read it as code. This:

shop.SellNotebooks(15);

is very straightforward; it means "Call the SellNotebooks method on the shop object, passing it 15 as a parameter." This:

shop.Sell(15)Notebooks

means... Well, what does it mean, exactly? It appears to call the Sell method on the shop object, but what's going on after that?

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Execution in the Kingdom of Nouns

In most single-dispatch object-oriented languages in common use today (such as Java and C++), the usual notation is noun-verb. That is, you take an object (a noun), and you apply a verb to it (a method). Doing things this way provides a consistent, easily understandable notation.

There have been a number of attempts to make such constructs more English-like, the most notable of which is the fluent interface. When it works well, it is a joy:

var query = translations
    .Where   (t => t.Key.Contains("a"))
    .OrderBy (t => t.Value.Length)
    .Select  (t => t.Value.ToUpper());

or

var sizer = Sizer.FromImage(inputImage)
     .ToLocation(outputImage)
     .ReduceByPercent(50)
     .OutputImageFormat(ImageFormat.Jpeg);

When it doesn't, well, not so much:

money.Add(20).Dollars().And().TransferTo().MyCheckingAccount().In(3).Days();

How does this work under the hood, exactly? Fluent interfaces are just like many other great ideas in computing; you can have too much of a good thing.

However, everyone understands this:

object.Verb(data);

And you don't have to squint that hard to figure out what it does.

Answer 2

There are quite a number of languages that have "keyword selectors". In those languages, arguments are passed after a colon inside the message selector. E.g., the following is valid syntax in (at least) Smalltalk, Self, Us, Korz, Fancy, Slate, Newspeak, Objective-C, Objective-C++, Objective-Modula-2, and possibly others:

anArray at: 3 put: "Hello".

This puts the string "Hello" at index 3 of anArray.

It is not quite what you want, though, since it only allows arguments after selector parts, not before.

I know I have seen a language that allows what you want somewhere, but I can't for the life of me remember the name.

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The answers to the related question mentioned in the comments above list a couple of languages that support your exact syntax: Agda, Inform7, TeX, Gherkin, robotframework scripting language.