Scala Development
Build runner
devtool is the default and detects the project itself. Drop to the underlying tool only when it is absent: use bloop if a .bloop directory exists (faster incremental), otherwise sbt. For non-modular projects the module name is root.
bloop compile <module-name>
bloop test <module-name> -o "*<filename>*"
sbt compile
sbt "testOnly *SpecName*"
Design opinions
These are Channing's preferred style and differ from the default choice:
Encapsulation over transparency: prefer class with private val (or opaque types) over case class when a type has internal structure that shouldn't be part of its public API (e.g. a Map tracking counts, a buffer, an index). Reserve case class for value types where every field is meaningful to callers (e.g. Book(title, author), Config(host, port)). Reaching for case class by default produces types that leak implementation details.
Typelevel ecosystem: prefer cats, cats-effect and fs2 over the alternatives (ZIO, Akka). This is a codebase consistency choice, not a judgement on the alternatives — mixing effect systems creates friction.
Red flag
A deliberate semantic divergence with no discriminating test. When behaviour intentionally differs from the mirrored precedent or the happy path — scale-insensitive BigDecimal equality, instant-based ZonedDateTime, extension-stack resolution in a repeating row — write the test that fails if the divergence regresses. The reviewer caught these every time; the implementer did not write them first.
