daml/UNRELEASED.md

Release of Daml DAML_VERSION

What’s New

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Minor Script warning

As part of the ongoing efforts to improve Scripts and the testing story around them, we've added a small warning for a test case that non-obviously doesn't run. Consider the following test:

myTest = script do
    ...
    error "Got here, and shouldn't have"

This test will not run, as it is implicitly polymorphic. Take a look at the type of error, it returns a, and as such, so does myTest. We cannot "run" this without making a a concrete type, so this cannot be run. We provide a warning in this case so a user may rectify this issue either by providing an explicit type signature, or by bounding the value of a in the call to script, via script @().

Restricted name warnings

Attempting to use the names this, self or arg in template, interface or exception fields will often result in confusing errors, mismatches with the underlying desugared code.
We now throw an error (or warning) early in those cases on the field name itself to make this more clear.

Note: Exception as well as templates without any choices did not previously throw errors for both self and arg. While using these names is discouraged, we only throw a warning here to avoid a breaking change. We may promote this to an error in future.

Dynamic Exercise

As part of extending the language to support evolving template definitions, we've added a new function dynamicExercise : HasDynamicExercise t c r => ContractId t -> c -> Update r, only available when targetting Daml LF version 1.dev. Currently, it operates just like exercise, but at a later stage it will instead use the most recent definition of template t choice c vetter by all stakeholders.

daml script --ide-ledger

In an effort to unify some of our internal and external tools, we now support the --ide-ledger option in daml script, allowing a user to directly invoke scripts within a dar file on their local machine, without a separate ledger running. Note the difference here with daml test being that daml script will not attempt to recompile or read the source code directly. This option cannot be used with --ledger-host, --participant-config or --json-api.