Category:M2000 Interpreter: Difference between revisions
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{{language|M2000 Interpreter
|exec=interpreted
|site=https://georgekarras.blogspot.com
|strength=both
|checking=dynamic
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|hopl=no
}}
M2000 is an interpreter running on its own Environment written in Visual Basic 6, as an open source project and can be found in GitHub[https://github.com/M2000Interpreter/Version9]. Current version is
{{language programming paradigm|Imperative}}
{{language programming paradigm|Object-oriented}}
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M2000 start as an experimental interpreted language, using a Module in Module idea (like a Procedure in Procedure) where each inner Module is closed for modification, but open for expansion, by replacing code at run time.
==English Vocabulary==▼
Module's may be Global, or local to other modules. We can define global modules in a module, and all these definitions deleted at the end of module execution. Because we have to execute the definition of a module, we can select definition, or load definition before we call the module. Also modules can be part of object's of type Group. A module can't call itself unless we use Call module_name. The standard call is by using only the name of module. So from a module we can call local modules or global, but we can't call parent module (if isn't global). In a group we can call anything like a module plus the modules of the groups.
We can change a inner module at the calling of a module, see the example: We call inner Beta in two stages. At the second stage we change inner Theta with Theta2. This is the decoration of Beta with Theta as Theta2. This is a temporary decoration because Beta after execution erase any new identifier including Theta. So each time we call Beta, statement Module Theta make this module unless a decoration stop it.
▲====English Vocabulary====
<syntaxhighlight lang="m2000 interpreter">Module Beta {
Module Theta (x){
Print "This is Theta, we get x=";x
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Print "This is Theta2, we get x=";x
}
Beta ; Theta as Theta2
</syntaxhighlight>
====Greek Vocabulary====
<syntaxhighlight lang="m2000 interpreter">Τμήμα Βήτα {
Τμήμα Θήτα (χ){
Τύπωσε "Αυτό είναι το Θήτα, θα πάρουμε το χ=";χ
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Τύπωσε "Αυτό είναι το Θήτα2, θα πάρουμε το χ=";χ
}
Βήτα ; Θήτα ως Θήτα2</
As we can see from code, some statements are like BASIC, except the use of curly brackets {}. Check the code below. We have a Module (as a Procedure), where we define some functions and some variables, as entities. These entities defined in every call to CheckIt, and erased when execution return from CheckIt. By default every parameter in M2000 pass by value. We define two functions, Alfa() where we set type for parameter x and ExpType$() where we not set type for x, and we wish to return the name of type when we make a call.
<syntaxhighlight lang="m2000 interpreter">Module CheckIt {
\\ We can't call something out of this module
Function Alfa(X as double) {
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M=Alfa(3)
Print Type$(M) ' Double
\\ If a variable get a type then any number convert to that type before assign to it
Z=121212112.11212@
Print Type$(Z)
Print Z1, Z2, Z3
Def ExpType$(x)=Type$(x)
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CheckIt
\\ Now Function Alfa and all variables erased.
CheckIt</
For small programs, for learning algorithms there is no need to use types, except the major types, Numeric and
Types are strong for values with a name (variables, constants), but weak for items in containers. In a container (Array, Inventory and Stack) we can place anything including other containers. We can bypass the "strong" capability but this isn't a practice for good programming. Internal or variables are of type of Variant, so we can make a reference of A to A$ and we can save a string "1212" and read from A the number 1212.
<syntaxhighlight lang="m2000 interpreter">
Module AKindOfMess {
a=10@
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Print Valid(12/0)=false ' evaluate expression and return true if is ok (errors trapped always)
Print Error$=""
</syntaxhighlight>
So check this for proper use of types.
<syntaxhighlight lang="m2000 interpreter">Module CheckInt {
A%=1212212.12@
Print A% ' 1212212
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Print B% ' 122121213
}
CheckInt</
So we say about Integer Variables, and no Integer Numeric Type. Like in Basic, M2000 is not case sensitive (except for labels), so A% and a% is the same. We may have A, A$ and A% as three variables, or A(), A%(), A$() as arrays or and functions. We can use name(@ ) to call function and not array if we have each with same name.
<syntaxhighlight lang="m2000 interpreter">Dim A(10)=1
Def A(x)=x**2
Print A(3), A(@ 4)</
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As we see alfa has no read statement, because before get the first number need to make two modules, and then pop one number and call a module passing current stack, so if choose beta, then the second value feed y from a read y statement.
<syntaxhighlight lang="m2000 interpreter">
module alfa {
module beta (y) {
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}
print sumall(1,2,3,4,5,6,7)=28
</syntaxhighlight>
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<syntaxhighlight lang="m2000 interpreter">Module Delta {
\\ Make a group like a lambda
\\ A Class make a Global Function
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Print Type$(P) ="Group"
}
Delta</
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a class define a type too. We can make a class from other classes too. We can make inner classes too.
<syntaxhighlight lang="m2000 interpreter">
Form 80,50
\\ counters supposed we provide them from a file
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}
}
</syntaxhighlight>
Until now we see modules/functions/subs for procedural programming, Groups for OOP, Groups as lambda functions and lambda functions for functional programming. We can use events for groups and for COM objects, including GUI objects.
<syntaxhighlight lang="m2000 interpreter">Module Beta {
Group WithEvents Alpha {
Event "One"
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Print M=111
}
Beta</
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Modules may have Threads, part of modules that can be executed in intervals, can be halted, or can be released, and can be erased. Each thread has own stack and may have own static variables (Modules and Functions also may have static variables), but can use modules variables and functions/modules/subs. Threads can run concurrent (thread return to task manager after execution of a statement or a block of statements) or sequential (a thread has to exit from interval to start other thread)
<syntaxhighlight lang="m2000 interpreter">Module Zeta {
k=10
Thread {
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Main.Task 100 {
Print k
Refresh // new versions do not insert automatic refresh for output in threads, we have to include it to code
If keypress(32) then Exit
}
}
Zeta</
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<syntaxhighlight lang="m2000 interpreter">Module Kappa {
Function Theta(x) {
Structure Points_single {
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Print Eval(P, 0!x)=1212.12~, Eval(P, 0!y)=21.1212~
}
Kappa</
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