purescript needs some JavaScript specific behaviors

[thautwarm]

https://github.com/purescript/purescript-effect/blob/master/src/Effect.js#L12

    return function () {
      return f(a())();
    };

where f is a purescript function. PureScript functions are curried, hence they must accept one and only one argument, but here they call it without arguments.

To speed up calling functions and making FFI easier, I think it could be better for each argument of purescript function has a default value () or None.

[lfkdsk]

@thautwarm we could add default value in PySExpr (when gen define).

[thautwarm]

@lfkdsk We have default values, and we re now using this for pspy.
See https://github.com/purescript-python/purescripto/blob/2598fa4cbe276db19235b308fedbd817fc89c090/purescripto/workaround.py#L9