ocaml

I am learning Jason Hickey's Introduction to Objective Caml . Here is an exercise I don't have any clue First of all, what does it mean to implement a dictionary as a function ? How can I image that? Do we need any array or something like that? Apparently, we can't have array in this exercise, because array hasn't been introduced yet in Chapter 3 . But How do I do it without some storage? So I don't know how to do it, I wish some hints and guides. I think the point of this exercise is to get you to use closures. For example, consider the following pair of OCaml functions in a file fun-dict.ml

I am looking for a code formatter or pretty printer for ocaml. Something like gofmt for the go programming language. It should preferably preserve comments. I am correcting hand-ins and some of the code is formatted in a way that makes it very hard to read. if you don't care about comments, you can use camlp4: camlp4 <file> -parser o -printer o > <new-file> Or you can use external indenter tools, as ocp-indent . 来源： https://stackoverflow.com/questions/12798723/ocaml-pretty-printer-code-formatter

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Why does this behavior occur? # Printf.sprintf ("Foo %d %s") 2 "bar";; - : string = "Foo 2 bar" # Printf.sprintf ("Foo %d" ^ " %s") 2 "bar";; Printf.sprintf ("Foo %d" ^ " %s") 2 "bar";; Error: This expression has type string but an expression was expected of type ('a -> 'b -> 'c, unit, string) format = ('a -> 'b -> 'c, unit, string, string, string, string) format6 I would expect that the string concatenation would be evaluated first, so everything will proceed as normal. Does this have to do with the type system trickery that Printf employs?

I am using Jane Street 's async_core by adding package(async_core) in _tags . When I use ocamlbuild -use-ocamlfind -I src test/test_airport.native , it gives me the following error: camlfind ocamlopt -linkpkg -package async_core -package unix -package netclient -package mongo -package xml-light src/airport.cmx test/test_airport.cmx -o test/test_airport.native ocamlfind: Error from package `threads': Missing -thread or -vmthread switch I googled it and here is what I got http://caml.inria.fr/pub/docs/manual-ocaml-4.00/manual039.html It says: Programs that use system threads must be linked as

I'm working on llvm OCaml bindings. I installed llvm package through opam ( opam install llvm ), when I use llvm in utop, I get the following error: #require "llvm";; Error: The external function 'llvm_global_succ' is not available. The opam llvm version is 3.2. I also tried building llvm3.3 from the official site ( ./configure --with-ocaml-libdir='ocamlc -where' ), the build was successful (all the llvm command-line tools are working), but I got the same error in utop. I'm on Mac OS 10.7.5. Edit: I solved it.. ocamlmktop -o llvmtop llvm.cma -cc g++ Then launch llvmtop , you can use llvm

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 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 1 :

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: How can I make a lazy list representing a sequence of doubling numbers? Example: 1 2 4 8 16 32 回答1: Using streams: let f x = Stream . from ( fun n -> Some ( x * int_of_float ( 2.0 ** float_of_int n ))) or let f x = let next = ref x in Stream . from ( fun _ -> let y = ! next in next := 2 * y ; Some y ) Using a custom lazy_list type: type 'a lazy_list = | Nil | Cons of ' a * 'a lazy_list lazy_t let rec f x = lazy (Cons (x, f (2*x))) 回答2: The great blog enfranchised mind has a great article on this topic: http://enfranchisedmind.com