That's great to hear! Whenever I searched for this, I only found an old
elm-dev post where implementing it was still being talked about.
I haven't really needed to write recursive loops in Elm yet. But in F#,
I've written a few.
On Thursday, October 13, 2016 at 11:21:50 PM UTC-5, Joey Eremondi wrote:
>
> One current limitation of Elm is that there is no tail call elimination
>
>
> Like Janis says, this is not true, and in most cases, tail-recursive
> functions will become while-loops in the resulting JS.
>
> For example, consider a list-summing function:
>
> sum : List Int -> Int
> sum =
> let
> helper accum lst =
> case lst of
> [] -> accum
> (h :: t) -> helper (h + accum) t
> in
> helper 0
>
> This gets turned into the following JS in 0.18 (though TCO has been around
> for a few versions):
>
> var _user$project$Main$sum = function () {
> var helper = F2(
> function (accum, lst) {
> helper:
> while (true) {
> var _p0 = lst;
> if (_p0.ctor === '[]') {
> return accum;
> } else {
> var _v1 = _p0._0 + accum,
> _v2 = _p0._1;
> accum = _v1;
> lst = _v2;
> continue helper;
> }
> }
> });
> return helper(0);
> }();
>
>
>
> On Thu, Oct 13, 2016 at 9:10 PM, Janis Voigtländer <[email protected]
> <javascript:>> wrote:
>
>> Your statement about tail call elimination is wrong. The Elm compiler
>> does it.
>>
>> Am 13.10.2016 um 23:38 schrieb Kasey Speakman <[email protected]
>> <javascript:>>:
>>
>> It probably sounds insane that Elm doesn't have `for` or `while`. It
>> would to me before exposure to functional programming.
>>
>> There are prebuilt functions for working with collections like List
>> <http://package.elm-lang.org/packages/elm-lang/core/latest/List> and
>> Array <http://package.elm-lang.org/packages/elm-lang/core/4.0.5/Array>
>> which will take care of most needs.
>>
>> When you find you need something a bit more custom, a recursive loop is
>> the normal way. Those take a little practice to get the feel for them.
>>
>> Often when I write my own recursive loop, I later find that I can
>> accomplish the same by combining list operations or by just playing with
>> List.foldr.
>>
>> One current limitation of Elm is that there is no tail call elimination
>> when using a recursive loop, so if you write your own loop and have a large
>> list, you can get a stack overflow. In practice, this is not a typical
>> problem due to other factors. I.e. miles of data on the screen impacts
>> performance, and is not considered good UX.
>>
>> On Wednesday, October 12, 2016 at 5:52:31 AM UTC-5, Patricia Nicole
>> Benedicto wrote:
>>>
>>> hi can i ask what is the repetiton control structucture of this
>>> programming languages?
>>>
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>
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