We use programming languages to indicate a process of actions/computations. Therefore programming languages tends to be more procedual. In other words, they are used to indicate how a thing is done.
Just as the role of verbs in a nature language sentence, an action is the most essential part of ‘doing a task’ in programming language. Of course the syntax of a programming language could be complex. I’d be here to discuss only the simplest cases of function calling among different programming languages.
Here’s a table of the terms used in different paradigms.
|Paradigm||Term for the Acting Object||Term for the Action|
Object Oriented Languages (Ruby, C++)
OOP is an analog of object manipulation in the real world. Actually,
foo.bar(baz) does not mean
foo does an action
baz. Rather, according to the OOP mechanism, it should be
regarded as a message
bar send to the actor
foo with argument
baz. Look at the code snippets below in Ruby and C++.
How would we translate them in English? The result is probably similar to these:
(The computer) puts “hello” on $stdout.
(The computer) pushes “hello” into vec.
In such invocations, obviously the subject is uslally omitted because we’re always ordering the computer to do the actions. The receivers, or target objects, are put at the front. Then follows the actions we want to apply on them. And finally the arguments, or carried objects.
Notice that the in Ruby the object is often omitted because it is
implied in the current context (
self). And in C++
sometimes omitted if we’re operating in a method within the same class.
It is similar to the case omitting object in a nature language when
we’re in a specific environment. For example, if we are working on a
task and then we say ‘finished’, the object can be understood as the
task we were working on.
Stack-based/Concatenative Languages (dc, Factor, Assembly)
The core of stack-based languages is the operation on a stack involves pushing and popping.
dc is a tiny calculator. The language of it is succinct and handy. Here’s an example:
The square brackets quotes a string of characters and push them into a
stack. Then the operation
p pops the string out and then prints it.
Stack-based language can be as simple as dc, while also can be as complex as Factor. Yet either of them have the same syntax structure. The following Factor code reverses an array.
We cannot directly translate them into one sentence of nature languages because the invocation of a function should not be regarded as a single process. As how we can see the process more clearly in Assembly language:
1 2 3
The invocation of such functions can be seen as a kind of argument-free operation. Their arguments are pushed to stack before the function invocations and in the function the arguments would be popped out to be manipulated.
If we still want to see the process of invocation as a single, we would derive a pattern that the actions, or the verbs, are always put at the last.
Functional languages (Scheme)
I consider the syntax of function invocation an opposition to the stack-based languages. Unlike the invocation syntax in stack-based languages, which put the action at the last, functional programming languages tend to pose the action/function as precedent to the arguments. I guess this phenomenon originates from the application syntax of FP’s ancestor lambda calculus.
In Scheme, a typical hello world program looks like:
It just looks like the stack-based language. In fact we can convert functional operations into stack operations through continuation-passing style transformation, so easily convertible into Assembly. In fact this technique is often used in Scheme compilers.