Fluid Script: Simple .NET server side scripting with browser breakpoints

FluidScript, a statically checked scripting language for .NET applications from developer jorgeleo, compiles scripts to verified, deterministic P-code that runs on a purpose-built virtual machine with capability-based embedding and no implicit file system, network, process, or CLR reflection access. The language targets .NET 10 and ships with a Monaco-based browser playground supporting editing, syntax highlighting, diagnostics, execution, source-level breakpoints, and detached debug checkpoints, which the documentation describes as "a development sample, not a production-ready multi-user execution service." Release helpers increment the patch version in fluid-script/FluidScript.csproj and create a Release package in artifacts/nuget/, persisting the version only after packaging succeeds.

FluidScript is a small, statically checked scripting language for .NET applications. It is designed for products that need approachable, user-authored automation or business rules without granting scripts ambient access to the file system, network, processes, or arbitrary CLR reflection. Scripts compile to verified, deterministic P-code and run on a purpose-built virtual machine. Your application explicitly chooses the functions, data, and CLR types a script may use. - Friendly authoring model — readable declarations, functions, types, arrays, dictionaries, string interpolation, JSON, error handling, and familiar if , while , for , and switch control flow. - Early, useful feedback — the compiler reports source-mapped diagnostics with stable codes before a script runs; runtime faults retain their source location and script function context. - Capability-based embedding — the host registers only the operations and CLR types it intends to expose. There is no implicit I/O, process, network, or reflection capability. - Predictable execution — a verified stack VM with configurable instruction limits, a bounded call depth, deterministic P-code serialization, and explicit values flowing across the host boundary. - Debuggable scripts — debug P-code preserves source spans. The VM can stop on source lines and create a portable, self-contained checkpoint that another process can validate and resume. function greeting name: string : string return "Hello, {name} " end dim names = "Ada", "Grace", "Lin" for index = 0 to 2 print greeting names index end The standard library is available automatically, including String , RegExp , Number , and Math : dim amount = Number.parseFloat "19.95" dim tax = Math.round amount 0.08 100 / 100 print "Total tax: {tax}" FluidScript fits well when an application needs controlled extensibility, for example: - configurable business rules, calculations, and validations; - workflow steps and domain-specific automation; - user-authored formulas and transformations over application-supplied data; - scripted behavior in a .NET desktop, service, or web application; and - an editor/playground experience with compiler diagnostics and source-level breakpoints. It is not a replacement for unrestricted application code. The host owns security policy, data access, and every external capability exposed to a script. Give untrusted scripts only narrowly scoped functions and a suitable instruction budget. FluidScript targets .NET 10. Build and run the test suite from the repository root: dotnet test FluidScript.sln --configuration Release --no-restore To try the included Monaco-based browser playground: dotnet run --project fluid-script-monaco/FluidScript.Monaco.csproj Open the local URL printed by ASP.NET Core normally http://localhost:5000 or https://localhost:5001 . The playground supports editing, syntax highlighting, diagnostics, execution, breakpoints, detached debug checkpoints, and JSON-native variable edits. It is a development sample, not a production-ready multi-user execution service. The release helpers increment the patch component in fluid-script/FluidScript.csproj , create a Release package in artifacts/nuget/ , and persist the version only after packaging succeeds. On Windows: pack-nuget.bat On macOS or another zsh host: ./pack-nuget.sh - User manual https://github.com/jorgeleo/fluid-script/blob/main/docs/user manual.md — learn the language, values, functions, flow control, JSON, imports, and the standard libraries. - Integration guide https://github.com/jorgeleo/fluid-script/blob/main/docs/integration.md — add FluidScript to a .NET project, execute and debug scripts, register application libraries/CLR types, persist P-code, and provide a module resolver. - Language contract https://github.com/jorgeleo/fluid-script/blob/main/docs/language.md — the normative language semantics and diagnostic behavior. - P-code format https://github.com/jorgeleo/fluid-script/blob/main/docs/pcode.md — serialization and detached-debugging contracts. - Monaco sample https://github.com/jorgeleo/fluid-script/blob/main/fluid-script-monaco/README.md — details of the browser playground and its HTTP protocol. import is intentionally host-resolved: an application supplies an IFluidModuleResolver that maps a script-visible name to source. Imports currently validate and compile dependencies, including missing-module and cycle detection. They do not yet execute modules, export symbols, or create script namespaces. Use explicit host capabilities for shared behavior until the staged module-linking features are available. fluid-script/ Compiler, P-code model, virtual machine, and host API fluid-script.test/ MSTest coverage for language and runtime behavior fluid-script-monaco/ ASP.NET Core Monaco playground docs/ User, integration, language, P-code, and architecture docs