I think I would opt for the very literal
type Bla
= A Int
| B Int
type BlaConstructor
= AConstructor
| BConstructor
blaConstructor : Bla -> BlaConstructor
blaConstructor bla =
case bla of
A _ ->
AConstructor
B _ ->
BConstructor
haveSameConstructor : Bla -> Bla -> Bool
haveSameConstructor firstBla secondBla =
blaConstructor firstBla == blaConstructor secondBla
The compiler will remind you to add a new case to the blaConstructor function
when you add a new Bla constructor, and that in turn will prompt you to add
a case to the BlaConstructor type - no tricky tuple matching required. I'm
also guessing you can come up with a more meaningful name than
'constructor' (perhaps 'kind' or something) that better indicates what it
actually means for an object to have a particular constructor.
On Monday, 17 July 2017 13:22:56 UTC-4, David Andrews wrote:
>
> Similar code, with new cases enforced by the compiler
>
> haveSameConstructor : Bla -> Bla -> Bool
> haveSameConstructor first second =
> case (first, second) of
> (A _, A _) -> True
> (B _, B _) -> True
> (A _, _) -> False
> (B _, _) -> False
>
> On Jul 17, 2017 3:34 AM, "Birowsky" <biro...@gmail.com <javascript:>>
> wrote:
>
>> That's not so bad. But the compiler wouldn't be able to nudge me to add a
>> new comparison when I add a new constructor in the Bla union.
>>
>> Thanx anyways.
>>
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