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Introduces c-rogueutil bindings example
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‎.github/actions/base/action.yml‎

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if: runner.os == 'Windows'
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uses: ./.github/actions/build-manual-windows
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- name: Build c-rogueutil example (Ubuntu)
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if: runner.os == 'Linux'
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uses: ./.github/actions/examples/c-rogueutil
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# Save the cache after building the project AND the manual.
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- name: Save cache
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uses: actions/cache/save@v4

‎.github/actions/examples/c-rogueutil/action.yml‎

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name: c-rogueutil Example
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description: Build and run the c-rogueutil example
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runs:
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using: composite
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steps:
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- name: Initialize git submodules
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shell: bash
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run: git submodule update --init --recursive examples/c-rogueutil/rogueutil
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- name: Run generation and build script
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shell: bash
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working-directory: ./examples/c-rogueutil
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run: ./generate-and-run.sh

‎.gitmodules‎

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[submodule "alternatives/c2hs"]
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path = alternatives/tools/c2hs
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url = https://github.com/haskell/c2hs.git
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[submodule "examples/c-rogueutil/rogueutil"]
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path = examples/c-rogueutil/rogueutil
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url = https://github.com/sakhmatd/rogueutil.git

‎examples/c-rogueutil/README.md‎

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# RogueUtil Haskell Bindings
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This example demonstrates generating Haskell bindings for the
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[rogueutil](https://github.com/sakhmatd/rogueutil) library, a cross-platform C
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library for terminal manipulation.
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## Quirks and Workarounds
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### 1. Disabling Shared Libraries (`shared: False`)
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The `generate-and-run.sh` script sets `shared: False` in `cabal.project.local` to prevent duplicate symbol errors during compilation.
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**Why this is needed:**
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RogueUtil is an unusual C library that defines function implementations
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directly in the header file (`rogueutil.h`) rather than in separate `.c`
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files. This is unorthodox C practice, but allows rogueutil to be a header-only
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library.
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When `hs-bindgen` generates bindings for such a library, it creates C wrapper
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functions that get embedded into multiple generated modules (Safe, Unsafe,
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FunPtr, Global). During dynamic library compilation, each module includes its
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own copy of these wrappers, causing "multiple definition" linker errors like:
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```
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ld: error: multiple definition of 'printXY'
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```
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Setting `shared: False` disables dynamic library building, preventing these
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conflicts. Static linking only includes each symbol once, avoiding the
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duplication problem.
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### 2. Enabling Modern C Standard (`-D_POSIX_C_SOURCE=200809L`)
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The binding generation command includes the clang option
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`-D_POSIX_C_SOURCE=200809L`:
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```bash
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--clang-option=-D_POSIX_C_SOURCE=200809L
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```
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This enables POSIX.1-2008 features that rogueutil depends on (such as
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`usleep`, `nanosleep`, and terminal control functions). Without this flag,
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clang would fail to parse the header due to missing standard library
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declarations.
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## Running the Example
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```bash
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./generate-and-run.sh
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```

‎examples/c-rogueutil/generate-and-run.sh‎

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#!/usr/bin/env bash
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# Exit on first error
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set -e
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
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echo "# "
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echo "# Building rogueutil C bindings"
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echo "# "
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cd "$SCRIPT_DIR/rogueutil"
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make
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echo "# "
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echo "# Generating Haskell bindings"
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echo "# "
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cd "$PROJECT_ROOT"
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cabal run hs-bindgen-cli -- \
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preprocess \
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-I "$SCRIPT_DIR/rogueutil" \
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--hs-output-dir "$SCRIPT_DIR/hs-project/src" \
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--module RogueUtil.Generated \
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--clang-option=-D_POSIX_C_SOURCE=200809L \
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"$SCRIPT_DIR/rogueutil/rogueutil.h"
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echo "# "
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echo "# Creating cabal.project.local"
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echo "# "
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cat > "$SCRIPT_DIR/hs-project/cabal.project.local" <<EOF
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package c-rogueutil
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extra-include-dirs:
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$SCRIPT_DIR/rogueutil
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extra-lib-dirs:
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$SCRIPT_DIR/rogueutil
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shared: False
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EOF
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echo "# "
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echo "# Done!"
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echo "# "
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echo "Running the project"
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cd $SCRIPT_DIR/hs-project
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export LD_LIBRARY_PATH=$SCRIPT_DIR/rogueutil/:\$LD_LIBRARY_PATH
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cabal build
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cabal run c-rogueutil

‎examples/c-rogueutil/hs-project/CHANGELOG.md‎

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# Revision history for c-rogueutil
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## 0.1.0.0 -- YYYY-mm-dd
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* First version. Released on an unsuspecting world.

‎examples/c-rogueutil/hs-project/LICENSE‎

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Copyright (c) 2024-2025, Well-Typed LLP and Anduril Industries Inc.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials provided
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with the distribution.
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* Neither the name of the copyright holder nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

‎examples/c-rogueutil/hs-project/app/Main.hs‎

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{-# LANGUAGE OverloadedStrings #-}
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module Main where
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import Control.Monad (forM_)
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import Foreign.C (newCString, withCString)
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import RogueUtil.Generated qualified as RU
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import RogueUtil.Generated.Safe qualified as Safe
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main :: IO ()
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main = do
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_ <- Safe.saveDefaultColor
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Safe.cls
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Safe.hidecursor
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Safe.setColor (fromIntegral $ RU.un_Color_code RU.YELLOW)
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Safe.setBackgroundColor (fromIntegral $ RU.un_Color_code RU.BLUE)
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titleStr <- newCString "=== RogueUtil Haskell Bindings Demo ==="
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Safe.printXY 20 2 (RU.RUTIL_STRING titleStr)
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Safe.resetColor
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rows <- Safe.trows
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cols <- Safe.tcols
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Safe.setColor (fromIntegral $ RU.un_Color_code RU.CYAN)
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sizeMsg <- newCString $ "Terminal size: " ++ show cols ++ "x" ++ show rows
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Safe.printXY 20 4 (RU.RUTIL_STRING sizeMsg)
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Safe.resetColor
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let colors = [RU.RED, RU.YELLOW, RU.GREEN, RU.CYAN, RU.BLUE, RU.MAGENTA]
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forM_ (zip [0..] colors) $ \(i, color) -> do
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Safe.setColor (fromIntegral $ RU.un_Color_code color)
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withCString ("█████ " ++ show color) $ \str ->
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Safe.printXY 20 (6 + fromIntegral i) (RU.RUTIL_STRING str)
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Safe.resetColor
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Safe.locate 20 14
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Safe.showcursor
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pressKeyMsg <- newCString "Press any key to exit..."
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Safe.anykey (RU.RUTIL_STRING pressKeyMsg)
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Safe.cls
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Safe.resetColor

‎examples/c-rogueutil/hs-project/c-rogueutil.cabal‎

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cabal-version: 3.0
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-- The cabal-version field refers to the version of the .cabal specification,
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-- and can be different from the cabal-install (the tool) version and the
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-- Cabal (the library) version you are using. As such, the Cabal (the library)
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-- version used must be equal or greater than the version stated in this field.
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-- Starting from the specification version 2.2, the cabal-version field must be
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-- the first thing in the cabal file.
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-- Initial package description 'c-rogueutil' generated by
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-- 'cabal init'. For further documentation, see:
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-- http://haskell.org/cabal/users-guide/
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--
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-- The name of the package.
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name: c-rogueutil
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-- The package version.
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-- See the Haskell package versioning policy (PVP) for standards
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-- guiding when and how versions should be incremented.
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-- https://pvp.haskell.org
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-- PVP summary: +-+------- breaking API changes
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-- | | +----- non-breaking API additions
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-- | | | +--- code changes with no API change
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version: 0.1.0.0
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-- A short (one-line) description of the package.
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-- synopsis:
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-- A longer description of the package.
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-- description:
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-- The license under which the package is released.
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license: BSD-3-Clause
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-- The file containing the license text.
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license-file: LICENSE
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-- The package author(s).
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author: Armando Santos
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-- An email address to which users can send suggestions, bug reports, and patches.
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maintainer: [email protected]
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-- A copyright notice.
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-- copyright:
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build-type: Simple
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-- Extra doc files to be distributed with the package, such as a CHANGELOG or a README.
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extra-doc-files: CHANGELOG.md
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-- Extra source files to be distributed with the package, such as examples, or a tutorial module.
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-- extra-source-files:
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common warnings
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ghc-options: -Wall
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library
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-- Import common warning flags.
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import: warnings
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-- Modules exported by the library.
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exposed-modules: RogueUtil.Generated
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RogueUtil.Generated.Safe
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RogueUtil.Generated.Unsafe
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RogueUtil.Generated.Global
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RogueUtil.Generated.FunPtr
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-- Modules included in this library but not exported.
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-- other-modules:
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-- LANGUAGE extensions used by modules in this package.
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-- other-extensions:
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-- Other library packages from which modules are imported.
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build-depends: base,
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hs-bindgen-runtime
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-- Directories containing source files.
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hs-source-dirs: src
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-- Base language which the package is written in.
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default-language: Haskell2010
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executable c-rogueutil
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-- Import common warning flags.
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import: warnings
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-- .hs or .lhs file containing the Main module.
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main-is: Main.hs
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-- Modules included in this executable, other than Main.
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-- other-modules:
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-- LANGUAGE extensions used by modules in this package.
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-- other-extensions:
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-- Other library packages from which modules are imported.
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build-depends:
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base,
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c-rogueutil
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-- Directories containing source files.
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hs-source-dirs: app
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-- Base language which the package is written in.
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default-language: Haskell2010

‎examples/c-rogueutil/hs-project/cabal.project‎

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packages: .
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../../../ansi-diff
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../../../hs-bindgen-runtime
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../../../c-expr-runtime
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../../../c-expr-dsl
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../../../hs-bindgen
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source-repository-package
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type: git
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location: https://github.com/well-typed/libclang
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tag: d4ae9a5fcca9ae71fcb4df2c0b0ea37c6b15c48c

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