Ref.read returns the old value after being written in a repl session

[edwardw]

In a Purescript REPL, reading a Ref after being updated returns the wrong answer if one types the inputs one line a time:

PSCi, version 0.13.6
Type :? for help

> import Prelude 
> import Effect.Ref as Ref
> import Effect.Unsafe
> ref = unsafePerformEffect $ Ref.new 0
> unsafePerformEffect $ Ref.write 1 ref
unit

> unsafePerformEffect $ Ref.read ref
0

But it does behave as expected if using :paste:

> :paste
… unsafePerformEffect do
…   ref <- Ref.new 0
…   Ref.write 1 ref
…   Ref.read ref
… 
1

This is most bizarre.

[hdgarrood]

This is to do with how the repl works, and not this library. Essentially, each time you enter a new command, the repl creates a module with all of the stuff you’ve entered, compiles it, and runs it.