## Megaparsec 5.1.0 * Defined `displayException` for `ParseError`, so exceptions are displayed in human-friendly form now. This works with GHC 7.10 and later. * Line comments parsed by `skipLineComment` now may end at the end of input and do not necessarily require a newline to be parsed correctly. See #119. * Exposed `parseErrorTextPretty` function in `Text.Megaparsec.Error` to allow render `ParseError`s without stack of source positions. * Eliminated the `old-tests` test suite — Parsec legacy. The cases that are not already *obviously* covered in the main test suite were included into it. ## Megaparsec 5.0.1 * Derived `NFData` instances for `Pos`, `InvalidPosException`, `SourcePos`, `ErrorItem`, `Dec`, `ParseError`, and `State`. * Derived `Data` instance for `ParseError`, `Data` and `Typeable` instances for `SourcePos` and `State`. * Minor documentation improvements. ## Megaparsec 5.0.0 ### General changes * Removed `parseFromFile` and `StorableStream` type-class that was necessary for it. The reason for removal is that reading from file and then parsing its contents is trivial for every instance of `Stream` and this function provides no way to use newer methods for running a parser, such as `runParser'`. So, simply put, it adds little value and was included in 4.x versions for compatibility reasons. * Moved position-advancing function from arguments of `token` and `tokens` functions to `Stream` type class (named `updatePos`). The new function allows to handle custom streams of tokens where every token contains information about its position in stream better (for example when stream of tokens is produced with happy/alex). * Support for include files (stack of positions instead of flat position) added. The new functions `pushPosition` and `popPosition` can be used to move “vertically” in the stack of positions. `getPosition` and `setPosition` still work on top (“current file”) level, but user can get full stack via `getParserState` if necessary. Note that `ParseError` and pretty-printing for it also support the new feature. * Added type function `Token` associated with `Stream` type class. The function returns type of token corresponding to specific token stream. * Type `ParsecT` (and also type synonym `Parsec`) are now parametrized over type of custom component in parse errors. * Parameters of `MonadParsec` type class are: `e` — type of custom component in parse errors, `s` — type of input stream, and `m` — type of underlying monad. * Type of `failure` primitive combinator was changed, now it accepts three arguments: set of unexpected items, set of expected items, and set of custom data. * Type of `token` primitive combinator was changed, now in case of failure a triple-tuple is returned with elements corresponding to arguments of `failure` primitive. The `token` primitive can also be optionally given an argument of token type to use in error messages (as expected item) in case of end of input. * `unexpected` combinator now accepts argument of type `ErrorItem` instead of plain `String`. * General performance improvements and improvements in speed of some combinators, `manyTill` in particular. ### Error messages * The module `Text.Megaparsec.Pos` was completely rewritten. The new module uses `Pos` data type with smart constructors to ensure that things like line and column number can be only positive. `SourcePos` on the other hand does not require smart constructors anymore and its constructors are exported. `Show` and `Read` instances of `SourcePos` are derived and pretty-printing is done with help of `sourcePosPretty` function. * The module `Text.Megaparsec.Error` was completely rewritten. A number of new types and type-classes are introduced: `ErrorItem`, `Dec`, `ErrorComponent`, and `ShowErrorComponent`. `ParseError` does not need smart constructors anymore and its constructor and field selectors are exported. It uses sets (from the `containers` package) instead of sorted lists to enumerate unexpected and expected items. The new definition is also parametrized over token type and custom data type which can be passed around as part of parse error. Default “custom data” component is `Dec`, which see. All in all, we have completely well-typed and extensible error messages now. `Show` and `Read` instances of `ParseError` are derived and pretty-printing is done with help of `parseErrorPretty`. * The module `Text.Megaparsec.ShowToken` was eliminated and type class `ShowToken` was moved to `Text.Megaparsec.Error`. The only method of that class in now named `showTokens` and it works on streams of tokens, where single tokes are represented by `NonEmpty` list with single element. ### Built-in combinators * Combinators `oneOf`, `oneOf'`, `noneOf`, and `noneOf'` now accept any instance of `Foldable`, not only `String`. ### Lexer * Error messages about incorrect indentation levels were greatly improved. Now every such message contains information about desired ordering between “reference” indentation level and actual indentation level as well as values of these levels. The information is stored in `ParseError` in well-typed form and can be pretty-printed when necessary. As part of this improvement, type of `indentGuard` was changed. * `incorrectIndent` combinator is introduced in `Text.Megaparsec.Lexer` module. It allows to fail with detailed information regarding incorrect indentation. * Introduced `scientific` parser that can parse arbitrary big numbers without error or memory overflow. `float` still returns `Double`, but it's defined in terms of `scientific` now. Since `Scientific` type can reliably represent integer values as well as floating point values, `number` now returns `Scientific` instead of `Either Integer Double` (`Integer` or `Double` can be extracted from `Scientific` value anyway). This in turn makes `signed` parser more natural and general, because we do not need ad-hoc `Signed` type class anymore. * Added `skipBlockCommentNested` function that should help parse possibly nested block comments. * Added `lineFold` function that helps parse line folds. ## Megaparsec 4.4.0 * Now state returned on failure is the exact state of parser at the moment when it failed, which makes incremental parsing feature much better and opens possibilities for features like “on-the-fly” recovering from parse errors. * The `count` combinator now works with `Applicative` instances (previously it worked only with instances of `Alternative`). It's now also faster. * `tokens` and parsers built upon it (such as `string` and `string'`) backtrack automatically on failure now, that is, when they fail, they never consume any input. This is done to make their consumption model match how error messages are reported (which becomes an important thing as user gets more control with primitives like `withRecovery`). This means, in particular, that it's no longer necessary to use `try` with `tokens`-based parsers. This new feature *does not* affect performance in any way. * New primitive parser `withRecovery` added. The parser allows to recover from parse errors “on-the-fly” and continue parsing. Once parsing is finished, several parse errors may be reported or ignored altogether. * `eitherP` combinator added. * Removed `Enum` instance of `Message` type. This was Parsec's legacy that we should eliminate now. `Message` does not constitute enumeration, `toEnum` was never properly defined for it. The idea to use `fromEnum` to determine type of `Message` is also ugly, for this purpose new functions `isUnexpected`, `isExpected`, and `isMessage` are defined in `Text.Megaparsec.Error`. * Minor tweak in signature of `MonadParsec` type class. Collection of constraints changed from `Alternative m, Monad m, Stream s t` to `Alternative m, MonadPlus m, Stream s t`. This is done to make it easier to write more abstract code with older GHC where such primitives as `guard` are defined for instances of `MonadPlus`, not `Alternative`. ## Megaparsec 4.3.0 * Canonicalized `Applicative`/`Monad` instances. Thanks to Herbert Valerio Riedel. * Custom messages in `ParseError` are printed each on its own line. * Now accumulated hints are not used with `ParseError` records that have only custom messages in them (created with `Message` constructor, as opposed to `Unexpected` or `Expected`). This strips “expected” line from custom error messages where it's unlikely to be relevant anyway. * Added higher-level combinators for indentation-sensitive grammars: `indentLevel`, `nonIndented`, and `indentBlock`. ## Megaparsec 4.2.0 * Made `newPos` constructor and other functions in `Text.Megaparsec.Pos` smarter. Now it's impossible to create `SourcePos` with non-positive line number or column number. Unfortunately we cannot use `Numeric.Natural` because we need to support older versions of `base`. * `ParseError` is now a monoid. `mergeError` is used as `mappend`. * Added functions `addErrorMessages` and `newErrorMessages` to add several messages to existing error and to construct error with several attached messages respectively. * `parseFromFile` now lives in `Text.Megaparsec.Prim`. Previously we had 5 nearly identical definitions of the function, varying only in type-specific `readFile` function. Now the problem is solved by introduction of `StorableStream` type class. All supported stream types are instances of the class out of box and thus we have polymorphic version of `parseFromFile`. * `ParseError` is now instance of `Exception` (and `Typeable`). * Introduced `runParser'` and `runParserT'` functions that take and return parser state. This makes it possible to partially parse input, resume parsing, specify non-standard initial textual position, etc. * Introduced `failure` function that allows to fail with arbitrary collection of messages. `unexpected` is now defined in terms of `failure`. One consequence of this design decision is that `failure` is now method of `MonadParsec`, while `unexpected` is not. * Removed deprecated combinators from `Text.Megaparsec.Combinator`: * `chainl` * `chainl1` * `chainr` * `chainr1` * `number` parser in `Text.Megaparsec.Lexer` now can be used with `signed` combinator to parse either signed `Integer` or signed `Double`. ## Megaparsec 4.1.1 * Fixed bug in implementation of `sepEndBy` and `sepEndBy1` and removed deprecation notes for these functions. * Added tests for `sepEndBy` and `sepEndBy1`. ## Megaparsec 4.1.0 * Relaxed dependency on `base`, so that minimal required version of `base` is now 4.6.0.0. This allows Megaparsec to compile with GHC 7.6.x. * `Text.Megaparsec` and `Text.Megaparsec.Prim` do not export data types `Consumed` and `Reply` anymore because they are rather low-level implementation details that should not be visible to end-user. * Representation of file name and textual position in error messages was made conventional. * Fixed some typos is documentation and other materials. ## Megaparsec 4.0.0 ### General changes * Renamed `many1` → `some` as well as other parsers that had `many1` part in their names. * The following functions are now re-exported from `Control.Applicative`: `(<|>)`, `many`, `some`, `optional`. See #9. * Introduced type class `MonadParsec` in the style of MTL monad transformers. Eliminated built-in user state since it was not flexible enough and can be emulated via stack of monads. Now all tools in Megaparsec work with any instance of `MonadParsec`, not only with `ParsecT`. * Added new function `parseMaybe` for lightweight parsing where error messages (and thus file name) are not important and entire input should be parsed. For example it can be used when parsing of single number according to specification of its format is desired. * Fixed bug with `notFollowedBy` always succeeded with parsers that don't consume input, see #6. * Flipped order of arguments in the primitive combinator `label`, see #21. * Renamed `tokenPrim` → `token`, removed old `token`, because `tokenPrim` is more general and original `token` is little used. * Made `token` parser more powerful, now its second argument can return `Either [Message] a` instead of `Maybe a`, so it can influence error message when parsing of token fails. See #29. * Added new primitive combinator `hidden p` which hides “expected” tokens in error message when parser `p` fails. * Tab width is not hard-coded anymore. It can be manipulated via `getTabWidth` and `setTabWidth`. Default tab-width is `defaultTabWidth`, which is 8. ### Error messages * Introduced type class `ShowToken` and improved representation of characters and strings in error messages, see #12. * Greatly improved quality of error messages. Fixed entire `Text.Megaparsec.Error` module, see #14 for more information. Made possible normal analysis of error messages without “render and re-parse” approach that previous maintainers had to practice to write even simplest tests, see module `Utils.hs` in `old-tests` for example. * Reduced number of `Message` constructors (now there are only `Unexpected`, `Expected`, and `Message`). Empty “magic” message strings are ignored now, all the library now uses explicit error messages. * Introduced hint system that greatly improves quality of error messages and made code of `Text.Megaparsec.Prim` a lot clearer. ### Built-in combinators * All built-in combinators in `Text.Megaparsec.Combinator` now work with any instance of `Alternative` (some of them even with `Applicaitve`). * Added more powerful `count'` parser. This parser can be told to parse from `m` to `n` occurrences of some thing. `count` is defined in terms of `count'`. * Removed `optionMaybe` parser, because `optional` from `Control.Applicative` does the same thing. * Added combinator `someTill`. * These combinators are considered deprecated and will be removed in future: * `chainl` * `chainl1` * `chainr` * `chainr1` * `sepEndBy` * `sepEndBy1` ### Character parsing * Renamed some parsers: * `alphaNum` → `alphaNumChar` * `digit` → `digitChar` * `endOfLine` → `eol` * `hexDigit` → `hexDigitChar` * `letter` → `letterChar` * `lower` → `lowerChar` * `octDigit` → `octDigitChar` * `space` → `spaceChar` * `spaces` → `space` * `upper` → `upperChar` * Added new character parsers in `Text.Megaparsec.Char`: * `asciiChar` * `charCategory` * `controlChar` * `latin1Char` * `markChar` * `numberChar` * `printChar` * `punctuationChar` * `separatorChar` * `symbolChar` * Descriptions of old parsers have been updated to accent some Unicode-specific moments. For example, old description of `letter` stated that it parses letters from “a” to “z” and from “A” to “Z”. This is wrong, since it used `Data.Char.isAlpha` predicate internally and thus parsed many more characters (letters of non-Latin languages, for example). * Added combinators `char'`, `oneOf'`, `noneOf'`, and `string'` which are case-insensitive variants of `char`, `oneOf`, `noneOf`, and `string` respectively. ### Lexer * Rewritten parsing of numbers, fixed #2 and #3 (in old Parsec project these are number 35 and 39 respectively), added per bug tests. * Since Haskell report doesn't say anything about sign, `integer` and `float` now parse numbers without sign. * Removed `natural` parser, it's equal to new `integer` now. * Renamed `naturalOrFloat` → `number` — this doesn't parse sign too. * Added new combinator `signed` to parse all sorts of signed numbers. * Transformed `Text.Parsec.Token` into `Text.Megaparsec.Lexer`. Little of Parsec's code remains in the new lexer module. New module doesn't impose any assumptions on user and should be vastly more useful and general. Hairy stuff from original Parsec didn't get here, for example built-in Haskell functions are used to parse escape sequences and the like instead of trying to re-implement the whole thing. ### Other * Renamed the following functions: * `permute` → `makePermParser` * `buildExpressionParser` → `makeExprParser` * Added comprehensive QuickCheck test suite. * Added benchmarks. ## Parsec 3.1.9 * Many and various updates to documentation and package description (including the homepage links). * Add an `Eq` instance for `ParseError`. * Fixed a regression from 3.1.6: `runP` is again exported from module `Text.Parsec`. ## Parsec 3.1.8 * Fix a regression from 3.1.6 related to exports from the main module. ## Parsec 3.1.7 * Fix a regression from 3.1.6 related to the reported position of error messages. See bug #9 for details. * Reset the current error position on success of `lookAhead`. ## Parsec 3.1.6 * Export `Text` instances from `Text.Parsec`. * Make `Text.Parsec` exports more visible. * Re-arrange `Text.Parsec` exports. * Add functions `crlf` and `endOfLine` to `Text.Parsec.Char` for handling input streams that do not have normalized line terminators. * Fix off-by-one error in `Token.charControl`. ## Parsec 3.1.4 & 3.1.5 * Bump dependency on `text`. ## Parsec 3.1.3 * Fix a regression introduced in 3.1.2 related to positions reported by error messages.