how to pattern match on an arbitrary number of arguments?
10,235
You can't match multiple arguments as such, but you can match tuples, so you can do:
let rec merge l1 l2 = match l1, l2 with
| [], lst
| lst, [] -> lst
| (n::ns), (m::ms) -> if n < m then n :: merge ns l2 else m :: merge l1 ms
If you're ok with the function taking its arguments as a tuple you can also use function
like this:
let rec merge = function
| [], lst
| lst, [] -> lst
| (n::ns as l1), (m::ms as l2) -> if n < m then n :: merge (ns, l2) else m :: merge (l1, ms)
Author by
Thomas Heywood
Updated on June 05, 2022Comments
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Thomas Heywood almost 2 years
Is there an OCaml equivalent to Haskell's pattern matching on an arbitrary number of arguments? For example, can I have something resembling:
merge [] lst = lst merge lst [] = lst merge l1 @ (n : ns) l2 @ (m : ms) = if n < m then n : merge ns l2 else m : merge l1 ms
(The example's lifted from Developing Applications with Objective Caml :)
Thanks.