ocaml

type exp = | CONST of int | VAR of var | ADD of exp * exp | SUB of exp * exp | ISZERO of exp | IF of exp * exp * exp | LET of var * exp * exp | PROC of var * exp | CALL of exp * exp and var = string type typ = TyInt | TyBool | TyFun of typ * typ | TyVar of tyvar and tyvar = string type typ_eqn = (typ * typ) list module TEnv = struct type t = var -> typ let empty = fun _ -> raise (Failure "Type Env is empty") let extend (x,t) tenv = fun y -> if x = y then t else (tenv y) let find tenv x = tenv x end let rec gen_equations : TEnv.t -> exp -> typ -> typ_eqn =fun tenv e ty -> match e with | CONST n

I tried to use Mutex module, such as Mutex.create(), but compiler says Unbound module Mutex. Does it require some special namespace? Thanks For toplevel : ocaml -I +threads # #load "unix.cma";; # #load "threads.cma";; # Mutex.create ();; - : Mutex.t = <abstr> For ocamlc : ocamlc -thread unix.cma threads.cma src.ml For ocamlopt : ocamlopt -thread unix.cmxa threads.cmxa src.ml For findlib : ocamlfind ocamlc -thread -package threads -linkpkg src.ml 来源： https://stackoverflow.com/questions/17188866/ocaml-mutex-module-cannot-be-found

I have implemented a pretty-printer for a module. Currently I start up utop , load the dependencies then do #install_printer pp_custom;; where pp_custom is the pretty-printer. I would like to automate this so that I can have it in a way that is similar to the lacaml library where the pretty-printer for the matrix is "installed" by default. How would I go about to doing that? In short, you need to run #install_printer directive whenever you load your library in the top. I'm using the following code to evaluate code in the toplevel: open Core_kernel.Std open Or_error let eval_exn str = let

I am trying to use Http_client.Convenience.http_post to make a http post request . The API is fairly simple: val http_post : string -> (string * string) list -> string Does a "POST" request with the given URL and returns the response body. The list contains the parameters send with the POST request. What I wish to do is to construct a http post request to get the flight information via google flights , explained as part 1 in here: http://www.nohup.in/blog/using-json-google-flights To maintain the format of the Post request , I took a screenshot as this: So finally, I construct a Http_client

This is the followup question of What's the grouping plan so that every two people are grouped together just once? Basically, I implemented the Round robin algorithm . By the algorithm, it can generate pairs list where each possible pair of elements are grouped together exactly once. For example, we have a, b, c, d , then On first day, we do a b c d Then we group like [(a,c);(b,d)]. Then we round it clockwise like a c d b Then we group like [(a,d);(c,b)]. Then we round it clockwise like a d b c Then we group like [(a,b);(d,c)]. (Note, a is fixed all the time.) Finally I can get [(a,c);(b,d)] [

I am actually sitting over a hour on a problem and don´t find a solution for it. I have this data type: type 'a tree = Empty | Node of 'a * 'a tree * 'a tree And i have to find a function which converts a given tree in a ordered list. There is also no invariant like that the left child has to be less then the right. I already found a "normal" recursion solution but not a tail recursive solution. I already thought about to build a unordered list and sort it with List.sort , but this uses a merge sort which is not tail recursive. Maybe someone has a good advice. Thank you! If you want to

I'm going on to writing a simple implementation of tic-tac-toe server (via telnet). The task - players connect to server and after they send START the server looks for a partner who typed START too, and game begins. A piece of code: let handle_income () = let con = Lwt_unix.accept sock in con >>= fun (cli, addr) -> let player = Lwt.return {state = Sleeping; descriptor = Lwt.return cli} in send_to_client player "Welcome to the server. To start game type in START and press Enter"; player;; let rec make_ready player = player >>= fun {state; descriptor} -> send_to_client player "Waiting for start