Couldn't match type 'Scenario' with 'Script'

Hi Damlers

I have a very simple Daml script that used to work:

test = script do
  alice <- allocateParty "Alice"
  p <- submit alice $ createCmd $ PersonContract {name = alice, address = Address {street = "RabbitStreet", city = "QueenOfHearts", country = "Wonderland"}, age = 7}
  submit alice $ do
    c <- fetch p
    assert $ c.name == alice

Trying to run it now i get the following error:

/root/organizer/daml/AddressBook.daml:32:3: error:
    • Couldn't match type 'Scenario' with 'Script'
        arising from a functional dependency between:
          constraint 'HasSubmit Script Update' arising from a use of 'submit'
          instance 'HasSubmit Scenario Update' at <no location info>
    • In the expression: submit alice
      In a stmt of a 'do' block:
        submit alice
          $ do c <- fetch p
               assert $ (getField @"name" c) == alice
      In the first argument of 'script', namely
        'do alice <- allocateParty "Alice"

What’s the reason for it?

Hi @nemanja,

First, just to avoid confusion: This was never a valid Daml Script. However, if you replace allocateParty by getParty and createCmd by create and script by scenario it is a valid scenario. So it broke by migrating it to a Script.

The reason for that is documented in the migration guide in point 5.2. Applying that switch from fetch to queryContractId, you end up with

test = script do
  alice <- allocateParty "Alice"
  p <- submit alice $ createCmd $ PersonContract {name = alice, address = Address {street = "RabbitStreet", city = "QueenOfHearts", country = "Wonderland"}, age = 7}
  Some c <- queryContractId alice p
  assert $ c.name == alice

You might also want to switch the last line to c.name === alice which provides you with a better error message on failure. Note that you need to add an extra import to DA.Assert for that to compile.