Well, there are lots of "do x" libs that I don't think a C programmer could easily copy, but hey, we're all Turing complete here... As for language features, historically Lisp was not always first for some particular feature, but because of earlier design decisions that still haven't been made by newer languages, it can usually implement innovative features from other languages or PL research papers as libraries without having to update the language spec or an implementation itself. So we have immutable collections, laziness, takes on pattern matching, various concurrency models, more sophisticated type systems...
One very recent library that might be of interest is "just" a new regex library (https://applied-langua.ge/posts/omrn-compiler.html) but it leverages one unique design choice Lisp made in that you have access to the language's compiler at runtime, it's not a fenced-off separate program only used to create a runtime executable. The compiler can (and in SBCL's case does) optimize and produce assembly code, SIMD instructions can be used too, so this regex lib is very fast while not being that much code.
> but it leverages one unique design choice Lisp made in that you have access to the language's compiler at runtime, it's not a fenced-off separate program only used to create a runtime executable.
This is best understood as having no phase separation between compile time and run time. Effectively, languages that are so designed do everything at compile time, up to and including running the actual program.
Though sometimes they can practically recover the phase separation by "extracting" a program that can be compiled in a single step and ran as a conventional binary. For example, a LISP program for doing math may support "extracting" a custom function evaluator or numerical-symbolic solver written in FORTRAN.
One very recent library that might be of interest is "just" a new regex library (https://applied-langua.ge/posts/omrn-compiler.html) but it leverages one unique design choice Lisp made in that you have access to the language's compiler at runtime, it's not a fenced-off separate program only used to create a runtime executable. The compiler can (and in SBCL's case does) optimize and produce assembly code, SIMD instructions can be used too, so this regex lib is very fast while not being that much code.