How do you make node modules available in the Purescript REPL?

Question

Is it possible to make all node modules available when running via pulp repl? It seems like some only work when invoked via pulp run.

I'm following the pattern in the Purescript Book: https://github.com/paf31/purescript-book/blob/master/text/chapter12.md

exports.fooImpl = function(onSuccess, onFailure) {
    return function() {
        require('some-lib').doThing(function(error, data) {
            if (error) onFailure(error.code)()
            else onSuccess(data)();
        }

    }
}

Purescript definitions:

foreign import fooImpl
  :: Fn2 
      (String -> Effect Unit)
      (ErrorCode -> Effect Unit)
      (Effect Unit)

foo:: (Either ErrorCode String -> Effect Unit) -> Effect Unit
foo path k =
  runFn3 readFileImpl
         path
         (k <<< Right)
         (k <<< Left)

Now if I hop into a REPL

pulp repl

and try to call my function, I get an error when I try to call the required library. .xxx is not a function

However, if I run via pulp run everything runs as expected and the node library function is called without issue.

Similarly, if I run a node repl and call the library directly I similarly experience no problems.

Interestingly, not all node libraries have this issue. Built ins like fs work fine, but third party ones are the ones that have trouble in the repl.

Is there a way to make these libraries available when running in the REPL?

rnons rnons · Accepted Answer · 2019-07-01T06:51:31

Do you have a reproducible example? It works for me. I will use https://github.com/nonbili/purescript-msgpack-msgpack as an example. Start pulp repl in the repo directory.

PSCi, version 0.12.5
Type :? for help

> import Msgpack
> encode' { x: 1 }
"¡x\1"

The implementation of encode' is

-- Msgpack.purs
foreign import encodeToString_ :: Json -> String
encode' :: forall a. EncodeJson a => a -> String
encode' = encodeToString_ <<< encodeJson

// Msgpack.js
var msgpack = require("@msgpack/msgpack");

exports.encodeToString_ = function(json) {
  return uint8ArrayToString(msgpack.encode(json));
};

How do you make node modules available in the Purescript REPL?

2 Answers

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