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Compiler or Language projects previously worked on
Some bugs and features that have been worked on previously:
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Expertise: ★★★☆☆
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Time: ★★★☆☆
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Mantis: None
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Mentor: Leo
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Who is working on this: @objmagic
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What needs to be done: Polymorphic variant types can be used to build other polymorphic variant types:
type foo = [ `A of int | `B of float ] type bar = [ foo | `C of string ]
It would be useful to do the same thing with object types:
type foo = < a: int; b: float > type bar = < foo; c: string >
Note that this will only work for exact (closed) object types.
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Status: Resolved
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Expertise: ?
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Time: ?
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Mantis: None
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Mentor:
-
What needs to be done: add support for
char-style range for integers (int,int32,int64andnativeint)let f = function | 0..100 -> true | _ -> false
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Status: Resolved
- Expertise: ★☆☆☆☆
- Time: ★★☆☆☆
- Mantis: 4799
- Mentor: ???
- Who is working on this: ???
- What needs to be done: document printf's treatment of width specifiers for the format specifiers
%b,%cand%a. Investigate the interaction of width specifiers with other format specifiers. See the Mantis issue for details. - Status: Resolved
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: 1956
- Mentor: ???
- Who is working on this: @stedolan
- What needs to be done: Check all external names have a "caml_" prefix and add C macros for backwards compatibility.
- Status: Resolved
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Expertise: ★★☆☆☆
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Time: ★★☆☆☆
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Mantis: 6396
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Mentor:
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Who is working on this:
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What needs to be done: If a warning marked as an error is emitted in the top-level by a phrase which also triggers a regular error, then the warning-error will instead be raised for the next phrase. For example,
$ ocaml -w +A -warn-error +A OCaml version 4.02.0+dev5-2014-04-29 # class c = object method x = 1 end;; class c : object method x : int end # class e = object inherit c method x = 3 method f = 1 + "x" end;; Warning 7: the method x is overridden. Error: This expression has type string but an expression was expected of type int # ();; Error: Some fatal warnings were triggered (1 occurrences)
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Status: Fixed by commit 837bcd6.
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Expertise: ★★★☆☆
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Time: ★★★☆☆
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Mantis:
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Mentor: Leo
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Who is working on this: @OlivierNicole
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What needs to be done: Currently, you cannot use
_in recursive bindings:# let rec _ = () and x = 3;; Characters 8-9: let rec _ = () and x = 3;; ^ Error: Only variables are allowed as left-hand side of `let rec'
This is because patterns aren't allowed there, only variables. Really
_should be considered a variable in this context. -
Status: Rejected
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: http://caml.inria.fr/mantis/view.php?id=7060
- Mentor:
- Who is working on this: @tadeuzagallo
- What needs to be done: See the Mantis issue for details. Here's an example of the current, undesirable behaviour:
# type t = A | B;;
type t = A | B
# let print_t fmt t = match t with A -> Format.fprintf fmt "A";;
Characters 20-60:
let print_t fmt t = match t with A -> Format.fprintf fmt "A";;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
B
val print_t : Format.formatter -> t -> unit = <fun>
# #install_printer print_t;;
# B;;
- : t = <printer print_t raised an exception>
- Status: resolved
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: http://caml.inria.fr/mantis/view.php?id=7150
- Mentor:
- Who is working on this:
- What needs to be done: When invoking the linker, ocamlopt reorders the user-specified and library-embedded options, changing the order of the library search path. See the Mantis issue for more details.
- Status: closed
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: 6258
- Mentor:
- Who is working on this:
- What needs to be done: No debug information is inserted for used in backtraces for %revapply and %apply primitives.
- Status: resolved
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Expertise: ★★☆☆☆
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Time: ★☆☆☆☆
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Mentor: @yallop
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Who is working on this: @objmagic
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What needs to be done: The compact local open syntax
M.()M.[]etc. makes it almost possible to override the list syntax, since[x1; x2; ... xn]desugars intox1 :: x2 :: ... xn :: [], and::and[]are resolved in the module M. This doesn't quite work currently because[]is not allowed as a user-defined constructor name (although::is). This change would give us convenient syntax for heterogeneous lists, for example:module H = struct type 'a hlist = [] : unit hlist | :: : 'a * 'b hlist -> ('a * 'b) hlist end let h = H.[1; "two"; false]
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Status: merged
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Expertise: ★☆☆☆☆
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Time: ★☆☆☆☆
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Mentor: @yallop
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Who is working on this: @objmagic
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What needs to be done: Add the following functions to the
BigarrayAPI:val kind_byte_size : ('a, 'b) kind -> int (** [kind_byte_size k] is the byte length of an element of kind [k]. *) val byte_size : ('a, 'b, 'c) t -> int (** [byte_size a] is [a]'s byte length. *)The function
byte_sizecan simply be implemented by exposing the existing C functioncaml_ba_byte_size -
Status: merged
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Expertise: ★★★☆☆
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Time: ★★★★☆
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Issue: https://github.com/OCamlPro/flambda-task-force/issues/92
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Mentor: Mark/Leo
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Who is working on this: @marklrh
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See the issue for details.
The worst part of this is probably fixing the Makefiles. They must be fixed properly (in particular, the lists of object files making up Flambda should not be duplicated, but shared with the toplevel Makefile.shared).
The rest is easy: in the Cmx_format.unit_infos type there is a field called ui_export_info, of type Export_info.t. The Export_info module has a printer that can be used with Format, e.g.
Format.eprintf "%a" Export_info.print_all cmx.ui_export_info
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Status: merged
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: None
- Mentor:
- Who is working on this:
- What needs to be done: Add punning for instance variable bindings in the object copying construct. The syntax
{< x; y >}should be equivalent to the expanded form
{< x = x; y = y >}- Status: merged
- Expertise: ★☆☆☆☆
- Time: ★★☆☆☆
- Mantis: None
- Mentor:
- Who is working on this:
- What needs to be done:
Printexc.get_raw_backtracein particular is new but is not marked as such in the ocamldoc at http://caml.inria.fr/pub/docs/manual-ocaml/libref/Printexc.html. - Status: merged
- Expertise: ★★★★☆
- Time: ★★★☆☆
- Mantis: 6219
- Mentor: Leo
- Who is working on this: Leo
- What needs to be done: The syntax is apparently already supported, but type checking is not yet supported.
- Status: This is likely to be included in the open types patch.
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: None
- Mentor: Leo
- Who is working on this: Thomas
- What needs to be done: Support some lighter syntax for functors. Currently you must write
functorfor each functor argument using this syntax:
module F = functor (X : S) -> functor (Y : T) -> struct end;;instead we should allow
module F = functor (X : S) (Y : T) -> struct end;;It might also be nice to have the top-level printer output this shortened version.
- Status: merged after discussion
- Expertise: ★☆☆☆☆
- Time: ★★☆☆☆
- Mantis: 6475
- Mentor:
- Who is working on this: vbgl
- What needs to be done: Currently
ocamlcignores the-ooption for C files. For example, the following command createscode.oin the current directory, not thebuilddirectory. - Status: merged
ocamlc -c -o build/code.o src/code.cThe task is to take -o into account when compiling C.
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: None
- Mentor: Leo
- Who is working on this: Thomas
- What needs to be done: Support some lighter syntax for functors in module types. Currently you must write
functorfor each functor argument using this syntax:
module type F = functor (X : S) -> functor (Y : T) -> T;;instead we should support:
module type F = functor (X : S) (Y : T) -> T;;It might also be nice to have the top-level printer output this shortened version.
- Status: merged after discussion
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: None
- Mentor: Leo
- Who is working on this: Thomas
- What needs to be done: Support some lighter syntax for functors in module types. Currently you must give a name to all functor arguments:
module type F = functor (X : S) -> T;;but if you do not need to use the argument then you should not have to name it. This would mean supporting:
module type F = functor S -> T;;In these cases it might also be reasonable to not require the functor keyword.
- Status: a less controversial version was merged after discussion. The parentheses are still needed, but you can now use an underscore when you don't want to name functor arguments:
module F = functor (_ : X) -> struct end- Expertise: ★★★☆☆
- Time: ★★★☆☆
- Mantis: 6318
- Mentor: Leo
- Who worked on this: Jeremy
- What needed to be done: Add the following construct
try
expr1
with
Exn -> expr2
| val p -> expr3The semantics of this is that if expr1 raises Exn then expr2 is evaluated. Otherwise the value of expr1 is bound to the pattern p and expr3 is evaluated. Note that this allows calls in expr3 to be tail calls, which can be very useful.
- Expertise: ★★☆☆☆
- Time: ★★★☆☆
- Mantis: 6228
- Mentor: Leo
- Who worked on this: Stephen
- What needed to be done: Stop the value printer (i.e. the part of the toplevel that prints values) from looping dozens of times on recursive values.
# let rec x = `Foo x;;
val x : [> `Foo of 'a ] as 'a =
`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
(`Foo
...))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))Resolution: patch submitted to Mantis. See also the pull request on Github.
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: 6112
- Mentor: Leo
- Who worked on this: Raphael
- What needed to be done: Remove the line number from error enabled warnings, or better yet, use the location of the warning itself.
$ cat error.ml
let a () = 3
let b () = 4
let c () = a(); b()
$ ocamlc -warn-error A error.ml
File "error.ml", line 4, characters 11-14:
Warning 10: this expression should have type unit.
File "error.ml", line 1:
Error: Error-enabled warnings (1 occurrences)
- Resolution: Patch submitted to mantis
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: 4919
- Who worked on this: vbmithr
- What needed to be done: add an inverse of the
unix_error_of_codefunction to unixsupport.c, unixsupport.h and the corresponding Windows files (unixsupport.c, unixsupport.h). - Resolution: Extended goswin's patch to the win32 version of unixsupport.{c,h}, wrote a simple test program for it and updated the issue on Mantis.
- Expertise: ★★☆☆☆
- Time: ★★☆☆☆
- Mantis: 6102
- Who worked on this: Jon Ludlam / Euan Harris
- What needed to be done: It would be occasionally useful to stop compilation just after parsing, or just after type-checking but without outputting anything unless there are errors, etc. A regular way to support this would be to allow stopping after any phase of the compiler (or at least: parsing, typing, lambda and cmm).
- Resolution: Wrote patch and updated the issue on Mantis
- Expertise: ★★☆☆☆
- Time: ★☆☆☆☆
- Mantis: 3725
- Who worked on this: vbmithr
- What needed to be done: Add "-impl-suffix" and "-intf-suffix" options to ocamldep that specify additional file extensions to be treated as ".ml" and ".mli" files respectively. This would make it much easier for ocamldep to handle generated source files. "-impl-suffix" should probably also be added to the compiler.
- Resolution: Found that "-ml-synonym" and "-mli-synonym" already existed for ocamldep. Updated the mantis issue to reflect this. Wrote a patch to add "-impl-suffix" to the compiler and created a Mantis issue for it (6110).
- Expertise: ★☆☆☆☆
- Time: ★☆☆☆☆
- Mantis: 5807
- Who worked on this: Jon Ludlam / Euan Harris / Mike McClurg
- What needed to be done: The is a Filename.chop_extension function that returns the part of the filename without the extension (e.g. "foo" from "foo.mli"). A function that returned the extension would also be useful.
- Resolution: A patch (actually two competing patches) were written and the mantis issue was updated.
- Expertise: ★★☆☆☆
- Time: ★★★☆☆
- Mantis: 3582
- Who worked on this: David Sheets
- What needed to be done: currently the literal denoting the integer following the highest representable value at a particular type is treated as a negative value:
# 4611686018427387904;;
- : int = -4611686018427387904
# 9223372036854775808L;;
- : int64 = -9223372036854775808L
# 2147483648l;;
- : int32 = -2147483648lInstead all out-of-range integer literals should be treated as errors:
# 4611686018427387904;;
Characters 0-19:
4611686018427387904;;
^^^^^^^^^^^^^^^^^^^
Error: Integer literal exceeds the range of representable integers of type intSee the discussion in Mantis 3302 for why this is not entirely trivial.
- Resolution: Xavier explicitly fixed this for int_of_string et al in 2009 but also acknowledged the lexing bug as intentional. We're not certain what the appropriate resolution is or why. See mantis for more details.
- Expertise: ★☆☆☆☆
- Time: ★☆☆☆☆
- Mantis: 5350
- Who worked on this: David Sheets
- What needed to be done: check the return code of
lseekin theread_trailerfunction and report a suitable error. - Resolution: Moved to close report as superfluous (regardless of codebase analysis). Xavier Leroy agreed it was superfluous, but fixed it anyway to make the code clearer (r13959).
- Expertise: ★★☆☆☆
- Time: ★☆☆☆☆
- Mantis: 6071
- Who worked on this: David Sheets
- What needed to be done: Add a "-no-init" option to the toplevel that prevents loading a ".ocamlinit" file.
- Resolution: A patch was written, submitted, and merged for a "-noinit" option to toploop and opttoploop.
- Expertise: ★★☆☆☆
- Time: ★☆☆☆☆
- Mantis: 3560
- Mentor: ?
- Who is working on this: Philippe https://github.com/ocaml/ocaml/pull/15
- What needs to be done: It seems that buffer already does enough checks to allow it to use
unsafe_blitinstead ofblit. Check whether this is the case, and then either add a patch to the Mantis issue or a comment explaining why it would not be safe. - Status: pull request submitted
- Expertise: ★☆☆☆☆
- Time: ★☆☆☆☆
- Mantis: 4539
- Mentor: ?
- Who is working on this: @nbraud proposed a (trivial) patch
- What needs to be done: We currently have this behaviour:
# sin < tan;;
Exception: Invalid_argument "equal: functional value".but we'd like this behaviour
# sin < tan;;
Exception: Invalid_argument "compare: functional value".
- Expertise: ★★☆☆☆
- Time: ★☆☆☆☆
- Mantis: 6182
- Mentor: Leo
- Who worked on this: Stephen
- What needed to be done: Give a more sensible error message for the case that a method is declared virtual within an immediate object. E.g.
# let o = object method virtual foo : int end;;
Error: This class should be virtual.
The following methods are undefined : foo- Resolution: A patch was written and a Mantis issue created for it, and the patch was merged.
- Expertise: ★★☆☆☆
- Time: ★★★☆☆
- Mantis: None
- Mentor: Leo
- Who is working on this: Mike McClurg, Jeremy
- What needs to be done: add support for user-defined infix constructors like (::+) or (::>). This mostly needs some small changes in the lexer and parser, as well as some simple changes to the top-level's value printer.
- Resolution: @drup has submitted a pull request
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Expertise: ★★★☆☆
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Time: ★★★☆☆
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Mantis:
-
Mentor:
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Who worked on this: @c-cube
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What needed to be done: It's easy at present to inadvertently turn tail calls into calls that consume stack space, leading to runtime errors when the previously tail recursive code runs out of stack. For example, changing
let rec foldl op acc = function [] -> acc | x :: xs -> foldl op (op x acc) xs
to add an exception handler
let rec foldl op acc = function [] -> acc | x :: xs -> try foldl op (op x acc) xs with Not_found -> assert false
changes the function so that it's no longer tail recursive.
Proposal: add support for an annotation
[@tailcall]that causes the compiler to emit a warning when added to a non-tail call. For example, annotating the recursive call tofoldlin the second implementation will result in a warning, because the call is not a tail call:let rec foldl op acc = function [] -> acc | x :: xs -> try foldl op (op x acc) xs [@tailcall] with Not_found -> assert false
The suggested implementation technique is to propagate the annotation through the compiler until the point at which the tail call is detected (e.g. when
APPTERMrather thanAPPLYis emitted). -
Status: Pull request merged