ocaml

问题 I am trying the Real World OCaml book. It talks about installing OPAM, then OCaml and Jane Street Core. I got utop loaded properly per the book instructions so that it automatically loads Core. Without Core, I can run a generic OCaml script simply by ocaml script.ml without compiling. But this doesn't work if the script uses Core. What's the right command if I want to run a Core based OCaml script without compiling? 回答1: Running a script that depends on additional libraries requires you to

问题 I'm porting my application from OCaml 4.02.3 to 4.03.0. Say you have the following in lexer.ml : type t = T [@@deriving sexp] let () = sexp_of_t |> ignore; print_endline "hai" I'm trying to run it as following: ocamlbuild -use-ocamlfind -pkg ppx_sexp_conv -cflags '-w @a-4-31' lexer.byte -- But I'm getting the following error: Warning 31: files lexer.cmo and /Users/vladimir/.opam/4.03.0+flambda/lib/ocaml/compiler-libs/ocamlcommon.cma(Lexer) both define a module named Lexer File "_none_", line

问题 One way to implement "early returns" in OCaml is via exceptions: exception Exit let myfunc () = try for i = 0 to .... do if .. then raise Exit done; false with Exit -> true However, is there a way to declare this Exit exception in the body of the function, so its name is not visible to other functions in the module? (* I would like to do this, but it gives a syntax error *) let myfunc () = exception Exit try for i = 0 to .... do if .. then raise Exit done; false with Exit -> true 回答1: Yes,

问题 I am writing a compiler for a functional language I designed with OCaml. I want my little language to have the feature of pattern matching, however, I got stuck in coming up with an algorithm to implement it. It seems really complicated as I dig into the problem. I can't find much useful information about the corresponding algorithm with google. I will be appreciated if someone can give me some hint or point me to the resources. Or are there any tricks to take advantage of OCaml's power in

问题 I am developing a protocol using TCP/IP socket in Ocaml and I am interested implementing the event driven approach. Basically, I want to make event handling functions that invokes whenever socket receives a new data or closed or opened. Is it possible to do in Ocaml without implementing it manually using multiple threads? Thanks, 回答1: Yes. Make a loop and use Unix.select to wait for events on your fds. You will have to set your sockets to non-blocking mode with Unix.set_nonblock so that your

问题 I'm trying to use pattern matching to write a calculator application. Two major types defined as below: type key = Plus | Minus | Multi | Div | Equals | Digit of int;; type state = { lcd: int; (* last computation done *) lka: key; (* last key actived *) loa: key; (* last operation actived *) vpr: int (* value print on the screen *) };; let print_state s = match s with state (a,_,_,d) -> print_int a; //Here has the compile error print_newline(); print_int d; print_newline();; However, if I

问题 type 'a node = | Nil | Cons of 'a * 'a t and 'a t = unit -> 'a node type 'a mappable = 'a t What does 'a t = unit -> 'a node mean in a type declaration? I thought that in a type declaration in ocaml we can only do an enumeration or call a constructor. thank you 回答1: unit -> 'a node is the type of a function that takes no argument and returns a 'a node (a node parameterized by 'a ). Example : let f () = Nil;; type 'a t = unit -> 'a node makes a synonym of the above type which is used in the

问题 I'm writing OCaml code that reads in a list and removes any char 'i's that appear at the beginning of the list. For instance, the list removeI['i';'i';'a';'c';'i'] should return -: int * char list = ['a';'c';'i'] , because there are 2 'i's at the beginning of the list. I believe I know how to implement this properly; however, I want to return a tuple that includes the number of removed 'i's as well as the new list with the 'i's removed. I know that may sound confusing, but an example would be

问题 I'm writing OCaml code that reads in a list and removes any char 'i's that appear at the beginning of the list. For instance, the list removeI['i';'i';'a';'c';'i'] should return -: int * char list = ['a';'c';'i'] , because there are 2 'i's at the beginning of the list. I believe I know how to implement this properly; however, I want to return a tuple that includes the number of removed 'i's as well as the new list with the 'i's removed. I know that may sound confusing, but an example would be

问题 I made a post here (ocaml llvm kaleidoscope tutorial "Unbound module LlvmExecutionEngine") but that issue does not seem present on my mac which I have switched to. I'm trying to get this to work: https://github.com/llvm-mirror/llvm/tree/master/examples/OCaml-Kaleidoscope/Chapter7 from this tutorial http://llvm.org/docs/tutorial/OCamlLangImpl7.html (I'm 99% sure these two are by the same people) After getting around a few issues I have reached a stumbling block for the last few hours of dyn