Pitometsu

utop#

module type T = sig
  type t = ..
end;;

module type T = sig type t = .. end

utop # 

Pitometsu

$ nix-shell -p gcc8 --command 'echo $NIX_CFLAGS_COMPILE'
-isystem /nix/store/aj932q5vd2xzl67v3qs6hsg47lxmf0n2-libc++-5.0.2/include -isystem /nix/store/89gnz8abjwra67d8y6s6ysmjl6ji81ai-libc++abi-5.0.2/include -isystem /nix/store/yr2vwrbjgabcskp153nzsyl72ysbfc1g-compiler-rt-5.0.2-dev/include -F/nix/store/7x42k0scp8xscrf092jalvpns4cwnnj3-swift-corefoundation/Library/Frameworks -isystem /nix/store/aj932q5vd2xzl67v3qs6hsg47lxmf0n2-libc++-5.0.2/include -isystem /nix/store/89gnz8abjwra67d8y6s6ysmjl6ji81ai-libc++abi-5.0.2/include -isystem /nix/store/yr2vwrbjgabcskp153nzsyl72ysbfc1g-compiler-rt-5.0.2-dev/include -F/nix/store/7x42k0scp8xscrf092jalvpns4cwnnj3-swift-corefoundation/Library/Frameworks

Pitometsu

(self: super:
  let
    # gcc = super.pkgs.gcc8;
    # gcc8 = super.pkgs.gcc8.override { stdenv = super.stdenv; };
    stdenv = super.stdenvAdapters.overrideCC super.stdenv super.pkgs.gcc8;
  in
    {
      inherit stdenv; # gcc8 gcc;
      # stdenv = super.overrideCC super.stdenv self.pkgs.gcc;
      # gcc8 = super.gcc8.override { stdenv = super.stdenv; };

Pitometsu

utop # let (module M) = (module Caml.Map.Make(Int64) : Caml.Map.S) in let to_ : unit -> _ M.t = fun () -> failwith "und" in to_;;
Error: This expression has type unit -> 'a M.t
       but an expression was expected of type 'b
       The type constructor M.t would escape its scope

utop # let module M = Caml.Map.Make(Int64) in let to_ : unit -> _ M.t = fun () -> failwith "und" in to_;;
- : unit -> 'a Map.Make(Core_kernel__Int64).t = <fun>

Pitometsu

let f (type k) : x:((module Caml.Map.S with type key = k) as 'a) -> y:'a -> z:k -> unit = fun ~x:(_) ~y:(_) ~z:(_) -> ();;
val f :
  x:(module Core.Caml.Map.S with type key = 'a) ->
  y:(module Core.Caml.Map.S with type key = 'a) -> z:'a -> unit = <fun>

Pitometsu

module type C = sig type 'a t = [>`C|`D] as 'a end
module type D = sig include C with type 'a t = [>`D] as 'a end
module rec C : C = C;;
module rec D : D = D;;
type c_t = (module C);;
type d_t = (module D);;
(fun (m : c_t) -> (m :> d_t)) (module C);;
- : d_t = <module>

Pitometsu

module type S = sig
  type t

  val of_string : string -> t
  val to_string : t -> string
end


let deser : 'a. (module S with type t = 'a) -> (_ -> 'a) * _ = fun m ->
  let module M = (val m) in

Pitometsu

utop # type t = unit -> (string, string, 'a) Map.t option constraint 'a = String.comparator_witness;;
type t = unit -> (string, string, String.comparator_witness) Map.t option

utop # let f : 'a. unit -> (string, string, 'a) Map.t option constraint 'a = String.comparator_witness = fun () -> failwith "hello";;
Error: Syntax error

utop # let f : unit -> (string, string, 'a) Map.t option constraint 'a = String.comparator_witness = fun () -> failwith "hello";;
Error: Syntax error

Pitometsu

mypkg = mkDerivation rec {
  name = "mypkg";
  version = "0.0.1";
  src = ./.;
  # ...
  outputs = [ "out" "custom" ];
  installPhase = ''
    mkdir -p $out
    do-some-install-to $out
    mkdir -pv $custom/share

Pitometsu

In file included from caml/custom.h:23:0,
                 from minor_gc.c:19:
minor_gc.c: In function 'alloc_shr_minor':
minor_gc.c:189:54: error: 'old_header' undeclared (first use in this function); did you mean 'Make_header'?
                  CAML_ALLOC_EFFECT_NONE, Profinfo_hd(old_header));
                                                      ^
caml/mlvalues.h:120:40: note: in definition of macro 'Profinfo_hd'
 #define Profinfo_hd(hd) (((mlsize_t) ((hd) >> PROFINFO_SHIFT)) & PROFINFO_MASK)
                                        ^~
minor_gc.c:189:54: note: each undeclared identifier is reported only once for each function it appears in