Thanks to people for their advices.
To my
>> I define
>> dropWhileInStr(p: Character -> Bool, xs: String) : String ==
>> empty? xs => ""
>> p first(xs) => dropWhileInStr(p, delete(xs, 1))
>> xs
>>
>> for dropping first letters from xs which satisfy a predicate p.
>> It this a reasonable code?
Waldek Hebish writes
> IMHO reasonable, but potentally quite inefficient: delete creates copy.
> If the string has length n delete allocates new string of length n-1
> and then copies characters.
> [..]
Is a string represented in FriCAS as a C array?
Is this total copying due to the array representation?
What may be an efficient code for dropWileInStr ?
(in Haskell, I never use arrays, somehow forgotten the style).
Consider the List approach:
dropWhile(p: Character -> Boolean, xs: List Character) :
List Character ==
empty? xs => xs
p first(xs) => dropWhile(p, rest xs)
xs
Is this more efficient?
I expect this variant will do much less copying (?).
This is, probably, similar to a list processing in Lisp,
and String probably works very differently.
-- ?
Regards,
------
Sergei
[email protected]
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