SmallBasic for Visual Studio Code

Microsoft Small Basic language support for Visual Studio Code (VS Code 1.96+).

repo: https://github.com/Ultramanhu/SmallBasicPlugin/

Features

• .sb file association with syntax highlighting (TextMate grammar + semantic tokens)
• IntelliSense completions, hover quick info and code outlining (collapsible regions)
• Live diagnostics in the Problems panel
• Navigation bar and outline view for procedures and variables
• Run programs with three backends in CLI mode, plus JavaScript and Blazor in Web mode:
  • SmallBasic: Run with JavaScript Backend — CLI mode uses the built-in JavaScript engine and terminal; Web mode runs TextWindow inside a browser Webview
  • SmallBasic: Run with C# Backend — bundled .NET run host; CLI mode only, with Windows graphics support (GraphicsWindow / Shapes / Turtle)
  • SmallBasic: Run with Blazor Backend — CLI mode uses the cross-platform host; Web mode runs Blazor WASM in a Webview with SVG graphics
• Debugging: breakpoints, stepping, variables (with SmallBasic array expansion) and call stack, shared DAP semantics across backends
• SmallBasic: New File command and Explorer context-menu template
• Localized Document

Language extension: procedures, loop control, integer division and modulo

Beyond classic Small Basic, the language core (C# and TypeScript implementations kept behavior-identical) adds procedural programming. All three run backends (JavaScript / C# / Blazor) support it:

• Function Name(A, B) … EndFunction — a value-returning procedure. Return expression exits immediately; reaching EndFunction without Return yields the empty string. Calls work anywhere a value is expected, including recursion and mutual calls.
• Sub Name(A, B) … EndSub — classic Subs now accept parameters, with the argument count checked exactly.
• Local scope — parameters and Dim-declared variables live in a per-call frame (recursion-safe, may shadow globals); undeclared names keep the classic global behavior.
• Parameterless procedures — declared as Sub F ≡ Sub F(); called as F ≡ F() and Answer = F ≡ Answer = F(). Procedures with parameters require parentheses and an exact argument count.
• Loop control — Break leaves the innermost While / For; Continue moves on to that loop's next iteration. A Continue inside a For still runs the step-increment and the bound check. Both only affect the innermost loop, and using either outside a loop reports BreakOutsideLoop / ContinueOutsideLoop.
• Integer division and modulo — A \ B truncates the quotient toward zero, while A Mod B returns a remainder with the dividend's sign. Math.Div(A, B) and Math.Mod(A, B) are exact method equivalents. A zero divisor returns 0 and execution continues.
• Precedence — the VB-style ladder is * / > \ > Mod > + -, with left associativity at each level. Mod is case-insensitive and reserved.
• Editor & debugger — coloring, completion, signature help and hover distinguish the Mod operator from the Math.Mod method. Arithmetic statements support breakpoints and stepping, and the new expressions work in conditional breakpoints, Watch and the Debug Console.

Sample (sample/hello/accumulate.sb):

Total = 0                          ' undeclared names stay global

Sub Accumulate(Value)              ' Subs accept parameters too
  Total = Total + Value            ' no Dim here -> this is the global Total
EndSub

Function Factorial(N)
  If N <= 1 Then
    Return 1
  EndIf
  Return N * Factorial(N - 1)      ' recursion
EndFunction

Accumulate(3)
TextWindow.WriteLine(Factorial(5)) ' prints 120

Loop control:

Sum = 0
For I = 1 To 5
  If I = 3 Then
    Continue                       ' skips only this iteration, the increment still runs
  EndIf
  If I = 5 Then
    Break                          ' leaves the loop before Sum grows again
  EndIf
  Sum = Sum + I
EndFor
TextWindow.WriteLine(Sum)          ' prints 7 (1 + 2 + 4)

Integer division and modulo:

Whole = 17 \ 5                    ' 3
Rest = 17 Mod 5                   ' 2
TextWindow.WriteLine(Math.Div(-7, 2)) ' -3
TextWindow.WriteLine(Math.Mod(-7, 2)) ' -1

Requirements

• The C# path requires the .NET 8 runtime and the Blazor path requires the .NET 8 and ASP.NET Core 8 runtimes.

Usage

• New file/Open: run SmallBasic: New File from the command palette, or open any .sb file — no project system required, "Open Folder" works.
• Edit: Syntax highlighting, completions, hover info, the Error List and code outlining are enabled automatically.
• Run: use the play button in the editor title bar, or the command palette.
• Debug: set breakpoints in a .sb file and press F5. You can pick a backend explicitly in launch.json:

CLI mode (the default; all three backends are available; the JavaScript backend support VSCode for Web, others only on desktop):

{ "type": "smallbasic", "request": "launch", "name": "SmallBasic [CLI]: Debug current file with JavaScript backend",
  "program": "${file}", "backend": "javascript", "mode": "cli", "stopOnEntry": false }

{ "type": "smallbasic", "request": "launch", "name": "SmallBasic [CLI]: Debug current file with C# backend",
  "program": "${file}", "backend": "csharp", "mode": "cli", "stopOnEntry": false }

{ "type": "smallbasic", "request": "launch", "name": "SmallBasic [CLI]: Debug current file with Blazor backend",
  "program": "${file}", "backend": "blazor", "mode": "cli", "stopOnEntry": false }

Web mode (JavaScript/Blazor; supported by desktop and VS Code for the Web):

{ "type": "smallbasic", "request": "launch", "name": "SmallBasic [Web]: Run current file with JavaScript backend",
  "program": "${file}", "backend": "javascript", "mode": "web", "stopOnEntry": false }

{ "type": "smallbasic", "request": "launch", "name": "SmallBasic [Web]: Run current file with Blazor backend",
  "program": "${file}", "backend": "blazor", "mode": "web", "stopOnEntry": false }

mode accepts cli or web. On desktop, cli is the default; choose web and use Run Without Debugging (Ctrl+F5) to run either the JavaScript or Blazor backend in the browser Webview. VS Code for the Web always uses web mode. JavaScript can still be debugged with F5; Blazor Web mode currently supports running only.

Settings

Known limitations

• The CLI JavaScript backend does not support graphics libraries (GraphicsWindow, Shapes, Turtle); use Web mode with Blazor or the Windows C# backend.
• The CLI debugging options are not supported in VSCode for Web.

License

MIT