SIP specifying Clarity slice function

[njordhov]

I propose a SIP to specify a slice function for Clarity, building on the proposal in clarity-lang/reference#42 expanded with the insights of stacks-network/stacks-core#3149. There is a prototype implementation of such a function in the next branch that can be improved on.

[obycode]

Can this be closed now with SIP-015?

[njordhov]

You may consider leaving it open as a candidate improvement for the next version of Clarity. The alternative design with last argument being the length of the result sequence offers a compelling alternative to the contrived expressions that typically results from the slice? function in SIP-015.

For example, consider this expression to just take the first three elements "abc" from a string while having the result properly typed as a (string-ascii 3):

(unwrap-panic (as-max-len? (default-to (list) (slice? "abcdef" 0 3)) u3))

With the proposed slice function, this would be written as below (with the last argument being the length of the result):

(slice "abcdef" 0 3)

[jcnelson]

Can this be closed now with SIP-015?

Yes it can.

You may consider leaving it open as a candidate improvement for the next version of Clarity.

Please open a specific issue for an alternative slice design. Thanks!