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This shows you the differences between two versions of the page.

--- mpl [2016/07/11 15:24] – [General Notes About Using The MPL] gryphon
+++ mpl [2016/07/13 21:27] (current) – g00r00
@@ Line 1: / Line 1: @@
 ====== Mystic Programming Language ======
- ===== General Notes About Using The MPL =====
+===== General Notes About Using The MPL =====
- The syntax of the Mystic BBS Programming Language follows closely to
+The syntax of the Mystic BBS Programming Language follows closely to
- that of the Turbo Pascal series of programming compilers.  At one time,
+that of the Turbo Pascal series of programming compilers.  At one time,
- the language was almost 100% Turbo Pascal compatible (except for the
+the language was almost 100% Turbo Pascal compatible (except for the
- BBS functions) but it has been slightly changed to make it a little
+BBS functions) but it has been slightly changed to make it a little
- more friendly to the programmer.
+more friendly to the programmer.
- Two versions of the programming compiler are available in the scripts
+Two versions of the programming compiler are available in the scripts
- directory.  The first one, MIDE.EXE, is a fully functional IDE for
+directory.  The first one, MIDE.EXE, is a fully functional IDE for
- creating and compiling MPE programs.  This program looks similar to the
+creating and compiling MPE programs.  This program looks similar to the
- Turbo Pascal IDE, including syntax highlighting of all command keywords!
+Turbo Pascal IDE, including syntax highlighting of all command keywords!
- The second version of the compiler is MPLC.EXE.  This is a command line
+The second version of the compiler is MPLC.EXE.  This is a command line
- compiler supplied so you are not forced to use MIDE.EXE to write
+compiler supplied so you are not forced to use MIDE.EXE to write
- programs.  If you do not find the MIDE interface to be satisfactory, then
+programs.  If you do not find the MIDE interface to be satisfactory, then
- you can use your favorite text editor and MPLC.EXE to create programs!
+you can use your favorite text editor and MPLC.EXE to create programs!
- The following are some quick notes about the syntax of the language as
+The following are some quick notes about the syntax of the language as
- well as some notes about things that aren't working as they probably
+well as some notes about things that aren't working as they probably
- should be:
+should be:
-  - All text after a two slashes (⁄⁄) is considered a comment.  It will be ignored until the next line of code.  For example: WriteLn ('Hello There')  ⁄⁄ This is a comment and will be ignored.
+==== Comments ====
+All text after a two slashes (⁄⁄) is considered a comment.  It will be ignored until the next line of code.  For example:
+  WriteLn ('Hello There')  ⁄⁄ This is a comment and will be ignored.
+==== Operation types ====
+The MPL does not follow the order of operations when doing mathmatical equations (ie PEMDAS - parenthesis, exponents, multiplication, division, addition, subtraction).  So math functions are done in the order that they appear in the expression.
+This doesn't mean its not POSSIBLE to do PEMDAS-ordered expressions, it will just take a little more effort on the programmer's behalf.
+The following operation codes are supported for mathematical equations:
+  − Subtract
+  + Addition
+  * Multiplication
+  ⁄ Division
+  % Modulus Operator
+==== Bitwise math ====
+MPL fully supports bitwise math and operators!  The following are implemented:
+  AND - Bitwise AND
+  OR  - Bitwise OR
+  XOR - Bitwise exclusive OR
+  SHL - Bitwise shift left
+  SHR - Bitwise shift right
+Example:
+  Const
+    UserDeleted = $00000004;  // Deleted bit from records.pas
+  Begin
+    GetThisUser;
+    If UserFlags AND UserDeleted <> 0 Then
+      WriteLn('User is deleted');
+  End;
+==== Defining Variables ====
+All variables are global to all of the program, including procedures.  The syntax for declaring a variable follows:
+  Var <Variable Name> : <Variable Type>
+  Examples:
+  Var Dummy : Byte;
+  Var Str   : String;
+  Var
+    Dummy1,
+    Dummy2  : Byte;
+The following variable types are supported:
+  Type            Format         Range
+  --------------- -------------- ----------------------------
+  Boolean         FALSE/TRUE     0..1
+  Char            Text           1 character
+  String          Text           Sequence of 1..255 characters
+  Byte            Numerical      0..255
+  Integer         Numerical      -32767..32767
+  Word            Numerical      0..65535
+  LongInt         Numerical      -2147483648..214748364
+  Cardinal        Numerical      0..4294967295
+  Real            Numerical      9.99
+All variables except ARRAYs can be initialized when when defined:
+  Var TotalBases : LongInt = GetMBaseTotal(False)
+  Var Int        : Integer = 33
+  Var Str        : String = 'This is a string'
+ARRAY multi-dimensional variables are supported.  The syntax for declaring an array variable is:
+  Var <VarName> : ARRAY[<Low>..<High>] of <VarType>
+  Var <VarName> : ARRAY[<L>..<H>, <L>..<H>] of <VarType>
+  Var <VarName> : ARRAY[<L>..<H>, <L>..<H>, <L>..<H>] of <VarType>
+Examples:
+  Var Dummy : Array[1..10] of Byte;
+  Var Str   : Array[5..10] of String;
+  Var Int   : Array[1..10, 1..10, 1..10] of Integer;
+HEXIDECIMAL values are supported.  They can be used in numeric variable assignment numerical evaluation, and in numeric constant variables.  A hex value must begin with a $ character:
+  Const
+    MyHexValue = $1F;
+  Value := $10;
+  If Value = $10 Then
+    WriteLn('Value is 16 <in decimal>');
+==== Record Structures ====
+Groups data in to records.  This command allows you to create a datatype of multiple different variable       types.
+Defining the record:
+  Type
+    testrec = record
+    x : byte;
+    y : byte;
+    d : array[1..10,1..5] of string[9]
+  end
+Declaring the record:
+  Var struct : testrec
+Using the record:
+  struct.x:=1
+  struct.y:=10
+  struct.d[1,1]:='abc123'
+  WriteLn(struct.d[1,1]);
+  WriteLn('struct.x='+Int2Str(struct.x))
+==== Code Blocks ====
+ When using multiple lines (more than one line) within a IF/ELSE/WHILE/CASE blocks, the lines need to be grouped into blocks between BEGIN and END statments.  If there is only one line following the IF/ELSE/WHILE/CASE blocks, then no blocking statements are needed.
+Examples:
+  If X = 1 Then
+    Begin
+      WriteLn('X = '+Int2Str(X))
+      X:=X+1
+      WriteLn('X = '+Int2Str(X))
+    End
+The same is true for the ELSE block.
+  If X = 1 Then
+    Begin
+      WriteLn('X = '+Int2Str(X))
+      X:=X+1
+      WriteLn('X = '+Int2Str(X))
+    End
+  Else
+    Begin
+      WriteLn('X = '+Int2Str(X))
+      X:=X-1
+      WriteLn('X = '+Int2Str(X))
+    End
+==== FOR LOOPS ====
+The syntax for a for loop is as follows:
+  For <variable> := <start number> <TO> or <DOWNTO> <end number> Do.
+  For A := 1 to 10 Do
+    WriteLn (A)
+  For A := 10 DownTo 1 Do
+    Begin
+      WriteLn (A)
+      WriteLn (A)
+    End
+==== REPEAT/UNTIL ===
+The syntax for a repeat until loop is as follows:
+  Repeat
+    <Code here>
+  Until <Boolean Expression>
+IE:
+  Repeat
+    WriteLn ('Blah blah')
+  Until A > 0 or A = 5
+==== WHILE ====
+The syntax for a while loop is as follows:
+  While <Boolean Expression> Do
+    <Code Here>
+IE:
+  While A > 0 and A = 5 Do
+    WriteLn ('Blah')
+OR:
+  While A > 0 and A = 5 Do
+    Begin
+      WriteLn ('Blah')
+      WriteLn ('More Blah')
+    End
+==== PROCEDURES ====
+The syntax for defining a procedure is as follows:
+  Procedure <Proc Name> (<varname vartype>, <varname vartype>)
+    <Code here>
+IE:
+  Procedure Hello_World
+    WriteLn ('Hello World')
+OR:
+  Procedure SomeProc (Str String, A Byte)
+    WriteLn ('Str = ' + Str)
+    WriteLn ('A   = ' + A)
+  End
+OR:
+  Procedure SomeProc (Str String)
+    Var
+      Str2 : String,
+      Str3 : String
+    Begin             <--- The keyword "BEGIN" is ignored by the compiler
+    WriteLn (Str)        just to maintain a "Pascal-like" feel.
+  End
+==== IF THEN/ELSE/END ====
+The syntax of an if/else/end statement:
+  If <boolean statement> Then
+    <True code here>
+  Else If <boolean statement> Then     (optional)
+    <True code here>
+  Else                            (optional)
+    <False code here>
+  If Not fEof(fptr) Then
+    WriteLn ('We''re not at the end of the file.')
+The above example is the same as the following example, except we've added an else statement:
+  If fEof(fptr) = False Then
+    WriteLn ('We''re not at the end of the file.')
+  Else
+    WriteLn ('This is the end of the file.')
+  If A = 1 Then
+    WriteLn ('A is 1')
+  Else If A = 2 Then
+    WriteLn ('A is 2')
+  Else If A = 5 Then
+    WriteLn ('A is 5')
+  Else
+    WriteLn ('A is not 1, 2, or 5...')
+==== CASE Statements ====
+This has actually been expanded on from the Pascal standard but still follows the same syntax.  It has been expanded to allow CASE of more variable types, such as strings.  See the included MPLTEST.MPS for examples.
+  Var I : Integer = 10
+  Case I Of
+: WriteLn('I = 1')
+: Begin
+         I:=I+1
+         WriteLn('I = 3')
+        End
+,4,5,6,7,8,9:
+      WriteLn('Not 1, 2, or 10')
+  End
+  Var S : String = 'ABCDEFG'
+    Case S[3] Of
+      'A': WriteLn('S[3] = '+S[3])
+      'B','C','D': WriteLn('S[3] = '+S[3])
+    Else
+       WriteLn('This is the default choice')
+    End
+==== FUNCTIONS ====
+The syntax for defining a function is as follows:
+  Function <Function Name> (<varname vartype>) : <result type>
+IE:
+  Function AddTen (Num Byte) : Byte
+  Begin
+    AddTen := Num + 10
+  End
+==== CONST VARIABLES ====
+The syntax for a constant variable is as follows:
+String constants:
+  Const
+    SomeStr = 'Hello World!'
+Numerical constants:
+  Const
+    SomeNum = 69
+Constant variables, like regular variables, can be separated with a comma:
+  Const
+    SomeNum = 69,
+    SomeStr = 'Hello World!'
+At the moment, constant variables cannot be used in certain places within the MPE engine.  If you are assigning a value to a variable, constant values will not be recognized.