https://github.com/jkachmar/purescript-lambda-demo

Test out calling Lambda functions directly from PureScript
https://github.com/jkachmar/purescript-lambda-demo

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Test out calling Lambda functions directly from PureScript

• Host: GitHub
• URL: https://github.com/jkachmar/purescript-lambda-demo
• Owner: jkachmar
• Created: 2017-12-08T01:20:15.000Z (about 7 years ago)
• Default Branch: master
• Last Pushed: 2017-12-08T05:39:03.000Z (about 7 years ago)
• Last Synced: 2024-11-07T04:49:36.316Z (2 months ago)
• Language: PureScript
• Size: 123 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
## PureScript Lambda Demo

A small demo to show how you can call PureScript from an AWS Lambda Handler.

All this demo does is accept an AWS Lambda event and attempt to extract a

a `String` from `payload.message`, passing the result off to Lambda's success

callback if it's successful or failing with a parse error if it's not.

### Build and Run the Demo

#### Building

To generate a Lambda function, clone this repository, install the dependencies 

using `npm`, and bundle up all the JS with webpack:

    git clone [email protected]:jkachmar/purescript-lambda-demo.git

    npm install

    npm run bundle

This will generate an output file at `dist/index.js` containing the full, 

bundled function.

#### Testing on Lambda

To run this demo on AWS Lambda, upload the file from `dist/index.js` like you 

would any other Lambda function, and test with the following test event payload:

    { "payload": { "message": "hello!" } }

...the handler will succeed:

![Success](images/success.png)

If a bad payload is supplied, for example with a `Boolean` at `payload.message`:

    { "payload" { "message": false } }

...the handler will fail:

![Failure](images/failure.png)

#### Testing Locally

To run this demo locally, open a `node` REPL in this directory and import the

bundled output:

    const { handler } = require('./dist/index.js');

Then call `handler` with a good payload, an empty argument, and a callback:

    handler({payload: {message: "hello!"}}, {}, (e, a) => { e ? console.log(e) : console.log(a); })

...and watch it succeed by printing the contents of `payload.message`:

    hello!

    

Alternatively, call `handler` with a bad payload, an empty argument, and a 

callback:

    handler({payload: {message: 0}}, {}, (e, a) => { e ? console.log(e) : console.log(a); })

...and watch it fail by printing the error and dumping an unhelpful stack trace:

```

Error: (NonEmptyList (NonEmpty (ErrorAtProperty "payload" (ErrorAtProperty "message" (TypeMismatch "String" "Number"))) Nil))

    at Object.exports.error (webpack:///./dist/index.js?:260:12)

    at eval (webpack:///./dist/index.js?:1520:122)

    at eval (webpack:///./dist/index.js?:552:22)

    at repl:1:1

    at ContextifyScript.Script.runInThisContext (vm.js:50:33)

    at REPLServer.defaultEval (repl.js:240:29)

    at bound (domain.js:301:14)

    at REPLServer.runBound [as eval] (domain.js:314:12)

    at REPLServer.onLine (repl.js:441:10)

    at emitOne (events.js:121:20)

```