Hi, First, i cannot understand what this mean and where we can use these expressions; let a = None let b = Some 10 what some mean ? let b=10 let c = Some true let d = Some "ok" Second, how can write this in ocaml let matchfunction x y z= match x y z with | | with the condition that function…

Some is a constructor of the option type. The definition is roughly: type 'a option = Some of 'a | None Which means that it either holds a value of some unspecified ('a) type (Some) or it is empty (None). So Some 10 is an int option, the Some true is a bool option and the Some "ok" is a string op…

Hi Rana, would you like some suggestions about where to find good learning resources for OCaml or ML-style functional programming?

OK. The best resource I can point you to is Prof. Dan Grossman’s free online course, ‘Programming Languages’: https://www.coursera.org/learn/programming-languages It has fantastic, short and to the point lecture videos that explain all the concepts really nicely. I think you will enjoy it. Note th…

[image] Leonidas: Which means that it either holds a value of some unspecified ( 'a ) type ( Some ) or it is empty ( None ). beginners question. But how do you extract the value if it does have a value? I tried this but obviously it shouldn’t work and it doesn’t but it portrays what I was go…

What do you expect the type of the resulting function to be? The first case (Some a -> a) suggests that it should be 'a, but the second case suggests that it should be 'a option. But it’s not allowed to be both. There are (at least) a few options here: Have your function take a default value of t…

is there no easy way to extract the value from Some constructor? like “indexing”?

I’m not sure I follow. I’ve described three ways of getting the value from an option. But I’m happy to elaborate or give examples, or maybe you could say more about what you’re trying to do.

Let’s rework your original function a bit: let get_option some_val = match some_val with | Some a -> a | None -> raise Not_found This is Levi’s item #2. This throws an exception at runtime if the option argument is actually None. If you’re OK with that, then sure, that works. It’s analogous to…

Basic questions in ocaml

Learning

talex5 October 3, 2017, 4:19pm 4

There are some useful links in the About the Learning category post. Feel free to suggest other things (though maybe we shouldn’t make it too long).

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An expression was expected of type unit because it is in the left-hand side of a sequence Learning	1	144	June 17, 2025
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Basic questions in ocaml

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