fable-compiler/ts2fable

Name: ts2fable

Owner: Fable

Description: Parser of Typescript declaration files

Created: 2017-03-25 23:21:25.0

Updated: 2018-04-01 10:30:42.0

Pushed: 2018-03-25 19:33:35.0

Homepage: null

Size: 1104

Language: F#

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README

ts2fable

Fable parser for TypeScript declaration files.

Usage

Install it with yarn or npm. With yarn it is:

 global add ts2fable

With npm it is:

install -g ts2fable

Run the ts2fable command on a TypeScript file and also specify the F# output file. The F# namespace in taken from the output filename. In this example, it is Yargs.

 add @types/yargs --dev
able node_modules/@types/yargs/index.d.ts src/Yargs.fs

You can also use --export(or -e) option to collect from multiple tsfiles

In below sample: All the related ts files in npm packages uifabric and office-ui-fabric-react will be compiled to OfficeReact.fs as a bundle

able node_modules/office-ui-fabric-react/lib/index.d.ts test-compile/OfficeReact.fs -e uifabric office-ui-fabric-react

You can find more information about how to interact with JavaScript from F# here. Please note the parser is not perfect and some tweaking by hand may be needed. Please submit bugs as issues on GitHub.

Contributing

Succesfull builds on the master branch are uploaded and tagged as next. You can help us test these builds by installing them with:

 global add ts2fable@next

Running code from source

Windows:

• git clone https://github.com/fable-compiler/ts2fable
• Install all dependencies: fake.cmd run build.fsx

Unix:

• git clone https://github.com/fable-compiler/ts2fable
• ./fake.sh run build.fsx

Common to all OS

• In vscode, press Ctrl+Shift+P > Run Task > WatchTest
• Add your test in test/fsFileTests.fs and prefix it with mocha only (See below sample)

Sample Test:

 "duplicated variable exports" <| fun _ ->
let tsPaths = ["node_modules/reactxp/dist/web/ReactXP.d.ts"]
let fsPath = "test-compile/ReactXP.fs"
testFsFiles tsPaths fsPath  <| fun fsFiles ->
    fsFiles
    |> getTopVarialbles
    |> List.countBy(fun vb -> vb.Name)
    |> List.forall(fun (_,l) -> l = 1)
    |> equal true

• Press F5 to debug this test

Conventions

Some JavaScript/TypeScript features have no direct translation to F#. Here is a list of common workarounds adopted by the parser to solve these problems:

• Erased unions: TypeScript union types work differently from F# and its only purpose is to specify the types allowed for a function argument. In F# they are translated as erased unions: they're checked at compiled time but they'll be removed from the generated JS code.

 CanvasRenderingContext2D =
abstract fillStyle: U3<string, CanvasGradient, CanvasPattern> with get, set

ctx: CanvasRenderingContext2D = failwith "dummy"
fillStyle <- U3.Case1 "#FF0000"

• Constructor functions: In JS any function can become a constructor just by calling it with the new keyword. In the parsed files, interfaces with this capability will have a Create method attached:

 CanvasRenderingContext2DType =
abstract prototype: CanvasRenderingContext2D with get, set
[<Emit("new $0($1...)")>] abstract Create: unit -> CanvasRenderingContext2D

• Callable interfaces: In the same way, JS functions are just objects which means applying arguments directly to any object is legal in JS. To convey, the parser attaches an Invoke method to callable interfaces:

 Express =
inherit Application
abstract version: string with get, set
abstract application: obj with get, set
[<Emit("$0($1...)")>] abstract Invoke: unit -> Application