AIGuiders.Platform.Modeling.Gdl.Expression 0.1.0

AIGuiders.Platform.Modeling.Gdl.Expression

A deliberately small expression AST — literals, fact references, comparisons, and boolean operators — for guarded conditions in declarative files.

What you get

• ExprNode — the neutral condition tree:
  • LiteralBool / LiteralString / LiteralInt
  • FactRef of string — reference to a named fact
  • Compare of ExprNode * string * ExprNode — left, string operator, right
  • And / Or / Not
• ExprSpan — source position (Line, Column); [<CLIMutable>] for C# construction
• ParsedExpr — node plus span, also [<CLIMutable>]
• Zero package dependencies — a pure type definition assembly

Quick start

open AIGuiders.Platform.Modeling.Gdl.Expression

// "build.failed and not review.open"
let condition : ExprNode =
    ExprNode.And(
        ExprNode.FactRef "build.failed",
        ExprNode.Not(ExprNode.FactRef "review.open"))

let parsed : ParsedExpr =
    { Node = condition
      Span = { Line = 3; Column = 7 } }

match parsed.Node with
| ExprNode.And _ -> printfn "guarded rule"
| _ -> ()

Problem

• Declarative files grow guarded conditions: when clauses in rule files, visibility conditions in layout decks, preconditions in command catalogs.
• Each grammar then either invents its own condition representation or embeds a general-purpose expression engine with far more power (and attack surface) than the grammar needs — and C# and F# consumers cannot share one tree.

Solution

• One deliberately tiny tree covers the whole condition language: three literal kinds, fact refs, a single comparison node, and boolean operators — deterministic, side-effect free, trivially walkable.
• [<CLIMutable>] records make the tree friendly to C# consumers; spans keep diagnostics anchored to the source file.
• This is the shared expression IR of the GDL family — the expressiveness ceiling for guarded rules is specified in GUIDERS-ADR-0057, and its F# extraction status is tracked in FSHARP-ADR-0003. In this repo the cockpit-logic graph parser (Modeling.Gdl.Parse.CockpitLogic) produces it and Modeling.Cockpit.Rules evaluates it.

When not to use

• No parser and no evaluator here — this package is only the AST; parsing lives in the Gdl.Parse.* packages and evaluation belongs to the consumer.
• Deliberately no arithmetic, string operations, function calls, or lambdas — if your conditions need those, this ceiling is the wrong tool.
• Comparison operators are unvalidated strings (">=", "=", …); operator semantics are a contract between your parser and evaluator, not this package.

Learn more

• GUIDERS-ADR-0057 — Cockpit logic quarry (expression ceiling)
• FSHARP-ADR-0003 — Model extraction matrix

MIT · Source & issues · part of the Guiders federation