dagger was originally CUE-based, but there was not enough demand so it was dropped. https://dagger.io/blog/ending-cue-support

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pxc 9 hours ago | parent [-]

> If you’ve been active in the Dagger community, this news will come as no surprise. Since we released multi-language support, we have seen a steep decline in usage of our original CUE configuration syntax, and have made it clear that feature parity with newer SDKs would not be a priority.

That is, of course, a self-fulfilling prophecy (or, perhaps, a self-inflicted wound). As soon as Dagger's "multi-language support" came out (actually a bit before), the CUE SDK was rendered abandonware. Development only happened on the new backend, and CUE support was never ported over to the new one.

	▲	shykes 6 hours ago \| parent [-]
		Dagger founder here. We moved away from CUE because the number one complaint from our early users was having to learn CUE. The number two complaint was bugs in the language that we diligently escalated upstream, but would never get fixed, including crippling memory leaks. We shipped multi-language support because we had no choice. It was a major engineering effort that we hadn't originally planned for, but it was painfully obvious that remaining a CUE-only platform was suicide.