Re: reverse a list. is this a good solution

Oke,

If I look it it seems to me that acc does the same as l2 on my
programm.

But does acc not have to be intialized on some way ?

Sébastien

then the outcome will be :

string list = ["c"; "b"; "a"; "1"; "2"; "3"]

so it reverse the second string and not the first one.

Roelof

Chingfan Tsao [email protected] [ocaml_beginners] schreef op
20-10-2014 15:55:

Hi,

It is indeed a good way to solve it since it's tail
recursion, however, there's one more thing to do to make
it easier, wrap it with a more convenient function:

let rev_list_tail_rec l =

let rec aux_rev l accum =

match l with

| [] -> accum

| h :: tl ->

aux_rev tl (h::accum)

in

aux_rev l []

this way, you can just use rev_list_tail_rec l
instead of having to give one more [] as the initial
value of the accumulator.

2014-10-20 18:56 GMT+08:00 Roelof
Wobben [email protected]
[ocaml_beginners] <[email protected] >:

Hello,

I try the 99 ocaml problems and have solved
the reverse a list problem.

My solution looks like this :

let rec test l1 l2 =

match l1 with

| [] -> l2

| h :: t -> test t (h::l2)

;;

Is this a good way to solve it or are there
things that can be better ?

Roelof

--

曹竞帆

哈尔滨工业大学计算机科学与技术专业本科在读

哈尔滨工业大学IBMTC成员

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Posted by: Roelof Wobben <[email protected]>
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