## Changelog

### 0.9.5 (unpublished)

- Provide Optional as a replacement for OrNil. Exports of the latter

  have been fixed.

- Provide utility function `raiseError`: Its argument will be thrown as

  an error in Lua.

- Add `modifyLuaError`: The function lives in Foreign.Lua.Error and

  allows to alter error messages. This is most useful for amending

  errors with additional information.

- Fixed a bug in `toList` which left a element on the stack if

  deserializing that element lead to an error. This also affected the

  FromLuaStack instance for lists.

- Fixed a bug in `pairsFromTable` which left a key-value pair on the

  stack if either of them could not be read into the expected type. This

  also affected the FromLuaStack instance for Map.

### 0.9.4

- Make Lua an instance of MonadMask: MonadMask from Control.Monad.Catch

  allows to mask asynchronous exceptions. This allows to define a

  finalizer for Lua operations.

- Add functions and constants to refer to stack indices: The functions

  `nthFromBottom`, `nthFromTop` as well as the constants `stackTop` and

  `stackBottom` have been introduced. Numeric constants are less clear,

  and named constants can aid readability.

- Add type OrNil: This type can be used when dealing with optional

  arguments to Lua functions.

- Add function absindex: it converts the acceptable index `idx` into an

  equivalent absolute index (that is, one that does not depend on the

  stack top). The function calls `lua_absindex` when compiled with Lua

  5.2 or later; for Lua 5.1, it is reimplemented in Haskell.

- Functions in `tasty` which have been deprecated have been replaced

  with non-deprecated alternatives.

### 0.9.3

- Re-export more FunctionCalling helpers in `Foreign.Lua`: The typeclass

  `ToHaskellFunction` and the helper function `toHaskellFunction` are

  useful when working with functions. Importing them separately from

  `Foreign.Lua.FunctionCalling` was an unnecessary burden; they are

  therefor now re-exported by the main module.

- Export registry-relatd constants `refnil` and `noref`: The constants

  are related to Lua's registry functions (`ref` and `unref`).

- Add helper to convert functions into CFunction: A new helper

  `wrapHaskellFunction` is provided. It expects a

  HaskellImportedFunction userdata (as produced by

  `pushHaskellFunction`) on top of the stack and replaces it with a C

  function. The new function converts error values generated with

  `lerror` into Lua errors, i.e. it calls `lua_error`.

- Add utility function `setglobal'`: It works like `setglobal`, but

  works with packages and nested tables (dot-notation only).

### 0.9.2

- Add cabal flag 'export-dynamic': Default behavior is to include all symbols in

  the dynamic symbol table, as this enables users to load dynamic lua libraries.

  However, it is sometimes desirable to disable, e.g., when compiling a fully

  static binary. See jgm/pandoc#3986.

### 0.9.1

- Increase user-friendlyness of error messages: The error message returned by

  `toHaskellFunction` hinted at the fact that the failing function is a Haskell

  function. This is mostly unnecessary information and might have confused

  users.

### 0.9.0

- Added cabal flag to allow fully safe garbage collection: Lua garbage

  collection can occur in most of the API functions, even in those usually not

  calling back into haskell and hence marked as optimizable. The effect of this

  is that finalizers which call Haskell functions will cause the program to

  hang. A new flag `allow-unsafe-gc` is introduced and enabled by default.

  Disabling this flag will mark more C API functions as potentially calling back

  into Haskell. This has a serious performance impact.

- `FromLuaStack` and `ToLuaStack` instances for lazy ByteStrings are added.

- None-string error messages are handled properly: Lua allows error messages to

  be of any type, but the haskell error handlers expected string values. Tables,

  booleans, and other non-string values are now handled as well and converted to

  strings.

### 0.8.0

- Use newtype definitions instead of type aliases for LuaNumber and LuaInteger.

  This makes it easier to ensure the correct numeric instances in situations

  where Lua might have been compiled with 32-bit numbers.

- Instances of `FromLuaStack` and `ToLuaStack` for `Int` are removed. The

  correctness of these instances cannot be guaranteed if Lua was compiled with a

  non-standard integer type.

### 0.7.1

- The flag `lua_32bits` was added to allow users to compile Lua for 32-bit

  systems.

- When reading a list, throw an error if the lua value isn't a table instead of

  silently returning an empty list.

### 0.7.0

- Tuples from pairs to octuples have been made instances of `FromLuaStack` and

  `ToLuaStack`.

- New functions `dostring` and `dofile` are provided to load and run strings and

  files in a single step.

- `LuaStatus` was renamed to `Status`, the *Lua* prefix was removed from its

  type constructors.

- The constructor `ErrFile` was added to `Status`. It is returned by `loadfile`

  if the file cannot be read.

- Remove unused FFI bindings and unused types, including all functions unsafe to

  use from within Haskell and the library functions added with 0.5.0. Users with

  special requirements should define their own wrappers and raw bindings.

- The module *Foreign.Lua.Api.SafeBindings* was merge into

  *Foreign.Lua.Api.RawBindings*.

- FFI bindings are changed to use newtypes where sensible, most notably

  `StackIndex`, `NumArgs`, and `NumResults`, but also the newly introduced

  newtypes `StatusCode`, `TypeCode`, and `LuaBool`.

- Add functions `tointegerx` and `tonumberx` which can be used to get and check

  values from the stack in a single step.

- The signature of `concat` was changed from `Int -> Lua ()` to

  `NumArgs -> Lua ()`.

- The signature of `loadfile` was changed from `String -> Lua Int` to

  `String -> Lua Status`. 

- The type `LTYPE` was renamed to `Type`, its constructors were renamed to

  follow the pattern `Type<Typename>`. `LuaRelation` was renamed to

  `RelationalOperator`, the *Lua* prefix was removed from its constructors.

- Add function `tolist` to allow getting a generic list from the stack without

  having to worry about the overlapping instance with `[Char]`.

### 0.6.0

* Supported Lua Versions now include Lua 5.2 and Lua 5.3. LuaJIT and Lua 5.1

  remain supported as well.

* Flag `use-pkgconfig` was added to allow discovery of library and include paths

  via pkg-config. Setting a specific Lua version flag now implies `system-lua`.

  (Sean Proctor)

* The module was renamed from `Scripting.Lua` to `Foreign.Lua`. The code is now

  split over multiple sub-modules. Files processed with hsc2hs are restricted to

  Foreign.Lua.Api.

* A `Lua` monad (reader monad over LuaState) is introduced. Functions which took

  a LuaState as their first argument are changed into monadic functions within

  that monad.

* Error handling has been redesigned completely. A new LuaException was

  introduced and is thrown in unexpected situations. Errors in lua which are

  leading to a `longjmp` are now caught with the help of additional C wrapper

  functions. Those no longer lead to uncontrolled program termination but are

  converted into a LuaException.

* `peek` no longer returns `Maybe a` but just `a`. A LuaException is thrown if

  an error occurs (i.e. in situtations where Nothing would have been returned

  previously).

* The `StackValue` typeclass has been split into `FromLuaStack` and

  `ToLuaStack`. Instances not satisfying the law `x == push x *> peek (-1)` have

  been dropped.

* Documentation of API functions was improved. Most docstrings have been copied

  from the official Lua manual, enriched with proper markup and links, and

  changed to properly describe hslua specifics when necessary.

* Example programs have been moved to a separate repository.

* Unused files were removed. (Sean Proctor)

### 0.5.0

* New raw functions for `luaopen_base`, `luaopen_package`, `luaopen_string`,

  `luaopen_table`, `luaopen_math`, `luaopen_io`, `luaopen_os`, `luaopen_debug`

  and their high-level wrappers (with names `openbase`, `opentable` etc.)

  implemented.

* Remove custom versions of `loadfile` and `loadstring`.

* Drop support for GHC versions < 7.8, avoid compiler warnings.

* Ensure no symbols are stripped when linking the bundled lua interpreter.

* Simplify `tostring` function definition. (Sean Proctor)

* Explicitly deprecate `strlen`. (Sean Proctor)

* Add links to lua documentation for functions wrapping the official lua C API.

  (Sean Proctor).

### 0.4.1

* Bugfix(#30): `tolist` wasn't popping elements of the list from stack.

### 0.4.0

* `pushstring` and `tostring` now uses `ByteString` instead of `[Char]`.

* `StackValue [Char]` instance is removed, `StackValue ByteString` is added.

* `StackValue a => StackValue [a]` instance is added. It pushes a Lua array to

  the stack. `pushlist`, `islist` and `tolist` functions are added.

* Type errors in Haskell functions now propagated differently. See the

  `Scripting.Lua` documentation for detailed explanation. This should fix

  segfaults reported several times.

* `lua_error` function is removed, it's never safe to call in Haskell.

Related issues and pull requests: #12, #26, #24, #23, #18.

### 0.3.14

* Pkgconf-based setup removed. Cabal is now using `extra-libraries` to link with Lua.

* `luajit` flag is added to link hslua with LuaJIT.

### 0.3.13

* Small bugfix related with GHCi running under Windows.

### 0.3.12

* `pushrawhsfunction` and `registerrawhsfunction` functions are added.

* `apicheck` flag is added to Cabal package to enable Lua API checking. (useful for debugging)

### 0.3.11

* `luaL_ref` and `luaL_unref` functions are added.