55 lines
2.0 KiB
TeX
55 lines
2.0 KiB
TeX
% Brittany-LE.tex
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\begin{hcarentry}[new]{Brittany}
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\report{Lennart Spitzner}%11/16
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\status{work in progress}
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\makeheader
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Brittany is a Haskell source code formatting tool. It is based on
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ghc-exactprint and thus uses the ghc parser, in contrast to tools based on
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haskell-src-exts such as hindent or haskell-formatter.
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The goals of the project are to:
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\begin{compactitem}
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\item
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support the full ghc-haskell syntax including syntactic extensions;
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\item
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retain newlines and comments unmodified (to the degree possible when code
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around them gets reformatted);
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\item
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be clever about using horizontal space while not overflowing it if it cannot
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be avoided;
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\item
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have linear complexity in the size of the input text / the number of
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syntactic nodes in the input.
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\item
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support horizontal alignments (e.g. different equations/pattern matches in
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the some function's definition).
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\end{compactitem}
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In contrast to other formatters brittany internally works in two steps: Firstly
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transforming the syntax tree into a document tree representation, similar to
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the document representation in general-purpose pretty-printers such as the
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\emph{pretty} package, but much more specialized for the specific purpose of
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handling a Haskell source code document. Secondly this document representation
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is transformed into the output text document. This approach allows to handle
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many different syntactic constructs in a uniform way, making it possible
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to attain the above goals with a manageable amount of work.
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Brittany is work in progress; currently only type signatures and function
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bindings are transformed, and not all syntactic constructs are supported.
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Nonetheless Brittany is safe to try/use as there are checks in place to
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ensure that the output is syntactically valid.
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Brittany requires ghc-8, and is not released on hackage yet; for a description
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of how to build it see the repository README.
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\FurtherReading
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{\small
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\begin{compactitem}
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\item
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\url{https://github.com/lspitzner/brittany}
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\end{compactitem}
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}
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\end{hcarentry}
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