Trulla 1.1.0

There is a newer version of this package available.
See the version list below for details.
dotnet add package Trulla --version 1.1.0                
NuGet\Install-Package Trulla -Version 1.1.0                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Trulla" Version="1.1.0" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Trulla --version 1.1.0                
#r "nuget: Trulla, 1.1.0"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install Trulla as a Cake Addin
#addin nuget:?package=Trulla&version=1.1.0

// Install Trulla as a Cake Tool
#tool nuget:?package=Trulla&version=1.1.0                

Trulla Templates

...an F# strongly typed text template provider!

Status: Still experimental

NuGet Badge

#r "nuget: Trulla, 0.0.0-alpha01"

open Trulla

let [<Literal>] TestTemplate = """
    Hello {{user.name}}, how are you?

    Your Orders
    ===

    {{for order in orders}}ID: {{order.id}}
    ({{if order.isActive}}active{{else}}inactive{{end}})
    ---
    {{end}}
    """

// All types required by the given template
// are infered and provided:
type Tmpl = Template<TestTemplate>

// Instanciate a typed model for the tempalte.
let templateModel =
    Tmpl.Root(
        [
            Tmpl.order(false, "Order 1")
            Tmpl.order(true, "Order 2")
        ],
        Tmpl.user("Hans"))

// Render and print it:
Tmpl.Render(templateModel) |> printfn "%s"

This will print:

    Hello Hans, how are you?

    Your Orders
    ===

    ID: Order 1
    (inactive)
    ---
    ID: Order 2
    (active)
    ---

The approach of Trulla is:

  • Provide a text template with:
    • template parameters
    • iterations
    • conditionals
  • A model type is infered from a given template.
  • An instance of the model is provided by the user for rendering the final template.

Limitations (current)

  • The model will only contain fields of type
    • list
    • string (for template holes)
    • bool
  • There are currently no partials supported

Implementation Notes

The implementation of the tempalte provider might be interesting, because it contains (in a simple form) the building blocks that are required for a programming language. It has:

A parser Parsing.fs implemented with FParsec. The parser output is a sequence of tokens:

type Token =
    | Text of string
    | Hole of PVal<MemberToken>
    | For of ident: PVal<string> * exp: PVal<MemberToken>
    | If of PVal<MemberToken>
    | Else
    | End
    
and MemberToken =
    | AccessToken of {| instanceExp: PVal<MemberToken>; memberName: string |}
    | IdentToken of string

An untyped AST Ast.fs that gets constructed from the parsed token sequence:


type TVar =
    | Root
    | TVar of int

type private BindingContext = Map<string, TVar>

type TVal<'a> =
    { 
        range: Range
        tvar: TVar
        bindingContext: BindingContext
        value: 'a 
    }
    override this.ToString() = sprintf "(%A)%A" this.range this.value

type TExp =
    | Text of string
    | Hole of TVal<MemberExp>
    | For of ident: TVal<string> * exp: TVal<MemberExp> * body: TExp list
    | If of cond: TVal<MemberExp> * body: TExp list
    | Else of cond: TVal<MemberExp> * body: TExp list

and Body = BindingContext * TExp list

and MemberExp =
    | AccessExp of {| instanceExp: TVal<MemberExp>; memberName: string |}
    | IdentExp of string

type Typ =
    | Mono of string
    | Poly of name: string * typParam: Typ
    | Field of Field
    | Record of TVar
    | Var of TVar

and Field = 
    { 
        name: string
        typ: Typ
    }

A solver Solver.fs that types records and identifiers of the AST

type RecordDef =
    {
        id: TVar
        fields: Field list
        name: string
    }

A generator (renderer) Rendering.fs that transforms all the previous into the final string.

TODOs

  • Shadowing (Explanation)
  • Wildcards in bindings
  • The begin and end character sequence for template expressions are configurable, and there is no way escaping them. Choose an appropriate sequence of characters that won't occur in your template.
Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.
  • .NETStandard 2.0

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Version Downloads Last updated
1.4.2 3,957 10/20/2023
1.4.1 207 10/18/2023
1.4.0-preview01 154 10/17/2023
1.3.0 185 9/18/2023
1.3.0-preview9 156 9/17/2023
1.3.0-preview8 154 9/17/2023
1.3.0-preview7 144 9/15/2023
1.3.0-preview6 155 9/15/2023
1.3.0-preview5 149 9/15/2023
1.3.0-preview4 148 9/15/2023
1.3.0-preview2 1,221 9/15/2023
1.3.0-preview18 117 9/18/2023
1.3.0-preview17 145 9/18/2023
1.3.0-preview16 129 9/18/2023
1.3.0-preview15 122 9/18/2023
1.3.0-preview14 137 9/18/2023
1.3.0-preview13 132 9/18/2023
1.3.0-preview12 135 9/18/2023
1.3.0-preview11 143 9/17/2023
1.3.0-preview10 148 9/17/2023
1.3.0-preview1 152 9/15/2023
1.2.1 180 9/13/2023
1.1.1 227 4/24/2023
1.1.0 213 4/24/2023

- 1.0.0
       Initial publish.
     
     - 1.0.1
       #5: Don't ref FSharp.Core 7
       #6: Stable ordering of ctor params
     
     - 1.1.0
       Revisiting / renaming to "Trulla"