Drop elements from each end of @racket[_lst] that satisfy @racket[_pred]. Exactly equivalent to @racket[(dropf-right (dropf _lst _pred) _pred)].
@examples[#:eval my-eval
(trimf '(1 2 3 a b c 4 5 6) integer?)
(trimf '(1 2 3 a b c) integer?)
(trimf '(a b c) integer?)
(trimf '(a b c 1 2 3 d e f) integer?)]
@defproc[
(filter-split
[lst list?]
[pred procedure?])
(listof list?)]
Like @racket[string-split], but for lists. Drop elements from anywhere in @racket[_lst] that satisfy @racket[_pred] — ends, middle, you name it — and return a list of the sublists that remain.
@examples[#:eval my-eval
(filter-split '(1 a b c 2 d e f 3) integer?)
(filter-split '(1 a b c 2 d e f 3) (compose notinteger?))
(filter-split '(a b c 1 2 3 d e f) integer?)
(filter-split '(a b c 1 2 3 d e f) (compose notinteger?))]
@defproc[
(frequency-hash
[lst list?])
hash?]
Count the frequency of each element in @racket[_lst], and return a hash whose keys are the unique elements of @racket[_lst], and each value is the frequency of that element within @racket[_lst].
@examples[#:eval my-eval
(frequency-hash '(a b b c c c))
(frequency-hash '(c b c a b c))
]
@defproc[
(members-unique?
[container (or/c list? vector? string?)])
boolean?]
Return @racket[#t] if every element in @racket[_container] is unique, otherwise @racket[#f].
@examples[#:eval my-eval
(members-unique? '(a b c d e f))
(members-unique? '(a b c d e f a))
]
@defproc[
(members-unique?/error
[container (or/c list? vector? string?)])
boolean?]
Same as @racket[members-unique?], but if the members are not unique, raises a descriptive error rather than returning @racket[#f].
A special version of @racket[when] that you can use inside @racket[quasiquote] to suppress @racket[void] values when @racket[_test] is @racket[#f]. As the name suggests, it works in conjunction with the @litchar["@"] splicing operator.
