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Thanks. I had not understood it could be recursive. Do you know Cons' meaning ? Also why does :: act as a separator... ? Is that something you ca do with an

Thanks. I had not understood it could be recursive. Do you know Cons' meaning ? Also why does :: act as a separator... ? Is that something you ca do with any Data constructor, I mean can I write type 'a = 'a Cons of 'a | Nil of 'a ?

willmorrison 5y ago
Here is the Wikipedia page: https://en.m.wikipedia.org/wiki/Cons https://en.m.wikipedia.org/wiki/Cons
gpderetta 5y ago
Cons comes from Lisp: https://en.wikipedia.org/wiki/Cons https://en.wikipedia.org/wiki/Cons . In practice a cons cell is a list node represented as a pair of pointers, one pointing to the contained element, the other to the next node (or null, or another element for degenerate lists).
maweki 5y ago
You would write something like List a = Cons a (List a) | Nil As :: doesn't start with a letter, it's infix by default. But basically a binary constructor. If you want to create the List [1,2,3] in the prefix notation you might be used to: ::(1,::(2,::(3,[])))