What is the best way to delete strings in a string list that that match certain pattern?

Peng Yu schrieb:

Suppose I have a list of strings, A. I want to compute the list (call
it B) of strings that are elements of A but doesn't match a regex. I
could use a for loop to do so. In a functional language, there is way
to do so without using the for loop.

Nonsense. For processing over each element, you have to loop over them,
either with or without growing a call-stack at the same time.

FP languages can optimize away the stack-frame-growth (tail recursion) - but
this isn't reducing complexity in any way.

So use a loop, either directly, or using a list-comprehension.