How to find if a string starts with one of several options in Clojure

user_10639446 0
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I want to find out if a string starts with one of several different options. For example, I want to know if a string starts with any vowel ("a" or "e" or "i" or "u").

I believe I should be using Clojure's starts-with?, but I don't know where to go from there. I have tried using a regular expression but couldn't get that right. I also tried using (or "a" "e" "i" "o" "u") but that also wasn't right.

EDIT: after more experimentation it seems that
(re-matches #"^[aeiou].*" string)
works, but I don't know if that's the best way to do it

clojure
2 Answers

Regex is fine. Without regex:

(contains? (set "aeiou") (first "apple"))
Borkdude_62640

To use starts-with?, you'd need to iterate the list of vowels. I'd use some for helping with this since you just care if some vowel is contained at the start of the string:

(some #(s/starts-with? "hello" (str %)) "aeiou")
=> nil

(some #(s/starts-with? "apple" (str %)) "aeiou")
=> true

Honestly though, I'd just do what @Michiel has already suggested and do a set lookup, although I'd do it a little differently:

(-> "apple"
    (first) ; Is the first letter
    #{\a \e \i \o \u}) ; In the set of vowels?
=> \a ; Truthy!

(-> "hello"
    (first)
    #{\a \e \i \o \u})
=> nil
user_30002060
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