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Category:M2000 Interpreter: Difference between revisions

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Category:M2000 Interpreter (view source)

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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. CodeSource code executed in one pass. Thereas is, awithout lowsecond range pass to determine the major typeinterpretation of an expression, a numbersimple orform, aalthough string.block Lookof thiscode paradigm:arranged Wefor call inner Betaexecution in twoa stages.manner Atof theconsuming secondcode stage(code wewhich changeexecuted innerdeleted, Thetacode within Theta2.a Thisloop is the decoration of Beta with Thetakept as Theta2. This is a temporarycopy decorationfor becausenext Beta after execution erase any new identifier including Thetaiteration). So each time we call Beta, statement Module Theta make this module unless a decoration stop it.
 
==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){
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Beta ; Theta as Theta2
</syntaxhighlight>
====Greek Vocabulary====
<syntaxhighlight lang="m2000 interpreter">Τμήμα Βήτα {
Τμήμα Θήτα (χ){
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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. Using DEF we can define variables and functions (in one line).
 
<syntaxhighlight lang="m2000 interpreter">Module CheckIt {
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M=Alfa(3)
Print Type$(M) ' Double
\\double Defz can create once// Znew (secondfrom timeversion raise error)12
Def Z as Double
\\ If a variable get a type then any number convert to that type before assign to it
Z=121212112.11212@
Print Type$(Z)
Def Currency Z1=212.12, Z2=323233.12, Z3=223212323323.12
Print Z1, Z2, Z3
Def ExpType$(x)=Type$(x)
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CheckIt
\\ Now Function Alfa and all variables erased.
\\// We can call it again
CheckIt</syntaxhighlight>
 
 
For small programs, for learning algorithms there is no need to use types, except the major types, Numeric and StringStrings, plus one more: Integer. Integers can be number types like Long and Integer types, or can be any numeric type using without decimal part. So Integer variables are variables with % atsuffix the end ofon their name. String Variable needcan use a $ atsuffix. From version 12 we can use string variables without suffix. Although the endinterpreter ofown namestring functions use suffix $ (like str$()).
 
For Expressions before execution automatic check by names if the result can be for strings names, or for numeric names. A string name has $ at the end of name. Maybe a string name isn't a string, because with same name we can define groups which get or and return strings values. A statement Input Alfa$ can input characters for a string or for object typed group with that name. Interpreter implicitly use the appropriate method. If name has no $ at the end then this can be an object or a numeric value. A Input Beta may return error if Beta has no numeric value to set.
 
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.
M2000
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