add nameof

Author: pchalamet

README.md

@@ -27,7 +27,7 @@ FScript currently includes:
 - pattern matching: list, option, tuple, record, union cases,
 - optional type annotations on parameters,
 - type declarations: records and unions (including recursive forms),
-- interpolation, pipeline operator, and `typeof` type tokens for host workflows.
+- interpolation, pipeline operator, `typeof` type tokens, and `nameof` identifier tokens for host workflows.
 
 ## Quick Start
 

docs/embedding-fscript-language.md

@@ -103,6 +103,18 @@ match value with
 | _ -> printfn "Not a function"
 ```
 
+## Using `nameof` for exported capability keys
+
+`nameof` returns the bound identifier name as a string and type-checks that the identifier exists.
+
+```fsharp
+open FScript.Language
+
+let src = "let run_step x = x\nnameof run_step"
+let value = FScript.run src
+// value = VString "run_step"
+```
+
 ## Supported types
 
 Host-visible static types are represented by `Type`:

docs/external-functions.md

@@ -33,7 +33,12 @@ Current runtime-handled groups include:
 
 ### Filesystem
 - `Fs.readText : string -> string option`
+- `Fs.combinePath : string -> string -> string`
+- `Fs.parentDirectory : string -> string option`
+- `Fs.extension : string -> string option`
+- `Fs.fileNameWithoutExtension : string -> string`
 - `Fs.glob : string -> string list option`
+- `Fs.enumerateFiles : string -> string -> string list option`
 
 ### Regex
 - `Regex.matchGroups : string -> string -> string list option`

docs/language-choices.md

@@ -49,6 +49,7 @@ let x =
 - Language core stays minimal.
 - Host capabilities are exposed through explicit extern functions.
 - Typed decoding workflows use `typeof Name` tokens with host externs.
+- Capability maps can use `nameof identifier` for stable script-side function keys.
 
 ## Formatting and layout choices
 - `match` case columns align.

docs/sandbox-and-security.md

@@ -15,7 +15,8 @@ This document defines the security model for running FScript programs with host
 - The CLI allows overriding root with `--root <path>` (or `-r <path>`).
 
 Filesystem extern behavior:
-- `Fs.readText` and `Fs.glob` resolve candidate paths through `HostCommon.tryResolvePath`.
+- `Fs.readText` and `Fs.enumerateFiles` resolve candidate paths through `HostCommon.tryResolvePath`.
+- `Fs.glob` evaluates patterns under `RootDirectory`.
 - Access is granted for paths within `RootDirectory` (or exactly equal to it).
 - Out-of-bound paths return `None`.
 

docs/supported-types.md

@@ -72,4 +72,5 @@ This document specifies the value and type system used by the interpreter.
 
 ## Reflection
 - `typeof Name` yields a type token.
+- `nameof identifier` yields the bound identifier name as `string`.
 - Type tokens are consumed by host externs (for example JSON/XML decoding).

docs/syntax-and-indentation.md

@@ -49,6 +49,7 @@ This document describes the concrete syntax accepted by the interpreter and the
 - Other:
   - `raise "message"`
   - `typeof Name`
+  - `nameof identifier`
   - interpolated strings `$"hello {name}"`
 
 ## Operator precedence

samples/types-showcase.fss

@@ -40,6 +40,12 @@ let updated = { user with Tags = user.Tags @ ["mathematician"] }
 // Inline structural annotation: any record with matching fields is accepted.
 let format_address (address: { City: string; Zip: int }) = $"{address.City} ({address.Zip})"
 
+// Name exposure for host capability maps.
+let capabilities =
+    Map.empty ""
+    |> Map.add (nameof format_address) "address formatting"
+    |> Map.add (nameof make_office_address) "office address constructor"
+
 
 let city =
     match updated.Address with
@@ -60,6 +66,7 @@ let monthlyPrice =
     | Free -> 0
     | Premium amount -> amount
 
+let missing = "missing"
 
 print $"User: {updated.Name}"
 print $"City: {city}"
@@ -72,6 +79,7 @@ print $"Subscription price: {monthlyPrice}"
 // - value created through another named record type (OfficeAddress)
 print $"Structural address from literal: {format_address parisAddress}"
 print $"Structural address from OfficeAddress: {format_address officeAddress}"
+print $"Capability for format_address: {Map.tryFind (nameof format_address) capabilities |> Option.defaultValue missing}"
 
 
 updated.Tags |> List.iter print

src/FScript.Language/Ast.fs

@@ -61,6 +61,7 @@ and Expr =
     | ESome of Expr * Span
     | ENone of Span
     | ETypeOf of string * Span
+    | ENameOf of string * Span
     | EInterpolatedString of InterpolatedPart list * Span
 
 and InterpolatedPart =
@@ -114,4 +115,5 @@ module Ast =
         | ESome (_, s) -> s
         | ENone s -> s
         | ETypeOf (_, s) -> s
+        | ENameOf (_, s) -> s
         | EInterpolatedString (_, s) -> s

src/FScript.Language/Eval.fs

@@ -470,6 +470,11 @@ module Eval =
             match typeDefs.TryFind name with
             | Some t -> VTypeToken t
             | None -> raise (EvalException { Message = $"Unknown type '{name}'"; Span = span })
+        | ENameOf (name, span) ->
+            if env.ContainsKey name then
+                VString name
+            else
+                raise (EvalException { Message = $"Unbound variable '{name}'"; Span = span })
         | EInterpolatedString (parts, span) ->
             let sb = System.Text.StringBuilder()
             for part in parts do