Triple library missing

[gampleman]

One of the types where an -extra library would be handy are triples (a, b, c).

Does it make sense to add such a library? Should it go into Tuple.Extra or should we make a new name for it? Triple.Extra?

Some candidate functions:

• triple : a -> b -> c -> (a, b, c)
• first : (a, b, c) -> a
• second : (a, b, c) -> b
• third : (a, b, c) -> c
• mapFirst, mapSecond, mapThird
• map : (a -> b) -> (a, a, a) -> (b, b, b)
• mapAll : (a -> x) -> (b -> y) -> (c -> z) -> (a, b, c) -> (x, y, z)
• from : a -> (a, a, a)
• and perhaps analogues of Tuple.Extra functions, although perhaps we could wait for demand there...

[ahankinson]

I would vote for adding it to the existing Tuple library, since the data type is a tuple, just with three values (not two).

[miniBill]

I'm not unconvinced it shouldn't just be called Triple

[lue-bird]

(too many negations...)

[miniBill]

I think we could just call it Triple