Brice

This seems to be intentional in the type_checker code. There is a related comment [here](https://github.com/stacks-network/stacks-blockchain/blob/59363a2dca5277bc01646bebcab98909c955bee1/src/vm/analysis/type_checker/natives/sequences.rs#L121): ```rust // we will only lookup native or defined functions here. // you _cannot_ map...

@reedrosenbluth pointed me to [SIP002](https://github.com/stacksgov/sips/blob/main/sips/sip-002/sip-002-smart-contract-language.md), quoted below, but I am not clear yet on why. > `filter` `map` and `fold` functions may only be called with user-defined functions (i.e., functions...

That makes sense. Thanks @kantai. Since the workaround is very easy (defining a wrapper function), adding that slightly more sophisticated type-checking can be low priority. Let's use this issue then...

We also should open an issue for the [documentation](https://docs.stacks.co/references/language-functions#filter) to explain this as well.

@lgalabru Is this a duplicate of #233?

It doesn't like you using `err` as a variable name. Using something else will work: ```clarity (define-public (get-save-rnd (block uint)) (match (map-get? RandomUintAtBlock block) rnd (ok rnd) (match (read-rnd block)...

But yes, `clarinet check` should catch that too. Thanks for reporting.

An, interesting. Thanks @LNow. I agree, clarinet check, the repl and the tests should all be the same as on chain. I'll take a look.

I think the problem returned after the addition of line numbers. There is no way to highlight just the code without also highlighting the line numbers. 

+1 this would be great!