init

.gitignore

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+
+
+# Created by https://www.gitignore.io/api/haskell,emacs
+
+### Haskell ###
+dist
+dist-*
+cabal-dev
+*.o
+*.hi
+*.chi
+*.chs.h
+*.dyn_o
+*.dyn_hi
+.hpc
+.hsenv
+.cabal-sandbox/
+cabal.sandbox.config
+*.prof
+*.aux
+*.hp
+*.eventlog
+.stack-work/
+cabal.project.local
+.HTF/
+
+
+### Emacs ###
+# -*- mode: gitignore; -*-
+*~
+\#*\#
+/.emacs.desktop
+/.emacs.desktop.lock
+*.elc
+auto-save-list
+tramp
+.\#*
+
+# Org-mode
+.org-id-locations
+*_archive
+
+# flymake-mode
+*_flymake.*
+
+# eshell files
+/eshell/history
+/eshell/lastdir
+
+# elpa packages
+/elpa/

LICENSE

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+Copyright (c) 2022, Gil Mizrahi
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Gil Mizrahi nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

app/Main.hs

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+import qualified Bulletin
+
+main :: IO ()
+main = Bulletin.main

readme.md

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+# Building a bulletin board using Haskell, twain and friends
+
+Check out the [blog post](https://gilmi.me/blog/post/2020/12/05/scotty-bulletin-board) for the scotty tutorial.
+This version uses [twain](https://hackage.haskell.org/package/twain) instead.
+
+## Run with
+
+
+```sh
+stack build && stack run
+```
+
+## Static executable
+
+To compile a static executable using docker, uncomment the relevant lines in the `stack.yaml` file,
+and rebuild with `stack build`.

src/Bulletin.hs

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+{-# language OverloadedStrings #-}
+
+-- | A bulletin board app built with twain.
+module Bulletin where
+
+import qualified Web.Twain as Twain
+import Network.Wai.Handler.Warp (run, Port)
+
+-- | Entry point. Starts a bulletin-board server at port 3000.
+main :: IO ()
+main = runServer 3000
+
+-- | Run a bulletin-board server at at specific port.
+runServer :: Port -> IO ()
+runServer port = do
+  putStrLn $ unwords
+    [ "Running bulletin board app at"
+    , "http://localhost:" <> show port
+    , "(ctrl-c to quit)"
+    ]
+  run port mkApp
+
+-- | Bulletin board application description.
+mkApp :: Twain.Application
+mkApp =
+  foldr ($)
+    (Twain.notFound $ Twain.send $ Twain.text "Error: not found.")
+    routes
+
+-- | Bulletin board routing.
+routes :: [Twain.Middleware]
+routes =
+  -- Our main page, which will display all of the bulletins
+  [ Twain.get "/" $
+    Twain.send $ Twain.text "not yet implemented"
+
+  -- A page for a specific post
+  , Twain.get "/post/:id" $
+    Twain.send $ Twain.text "not yet implemented"
+
+  -- A page for creating a new post
+  , Twain.get "/new" $
+    Twain.send $ Twain.text "not yet implemented"
+
+  -- A request to submit a new page
+  , Twain.post "/new" $
+    Twain.send $ Twain.text "not yet implemented"
+
+  -- A request to delete a specific post
+  , Twain.post "/post/:id/delete" $
+    Twain.send $ Twain.text "not yet implemented"
+  ]

stack.yaml

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+resolver: nightly-2022-04-06
+
+# uncomment for static executables
+# docker:
+#   enable: true
+#   image: utdemir/ghc-musl:v24-ghc922
+
+packages:
+- .
+
+extra-deps:
+- twain-2.1.0.0
+
+allow-newer: true

stack.yaml.lock

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+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages:
+- completed:
+    hackage: twain-2.1.0.0@sha256:9b434a5290791ab370845ded0d2167377cdc1478a592b87c5f5a9d499d069ba3,1864
+    pantry-tree:
+      size: 500
+      sha256: 09cd5490f751e8740f294483d02987a2a387b7dfd4b0db0b0d66c9cd391a9d48
+  original:
+    hackage: twain-2.1.0.0
+snapshots:
+- completed:
+    size: 545843
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2022/4/6.yaml
+    sha256: e59512928378e2411fea0269b3a658e31c8b24c9824dc213361dcce50a2b3f29
+  original: nightly-2022-04-06

twain-bulletin-app.cabal

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+name:                twain-bulletin-app
+version:             0.1.0.0
+synopsis:            A simple bulletin board web app using twain
+description:         Please see readme.md
+homepage:            https://github.com/soupi/learn-twain-bulletin-app
+license-file:        LICENSE
+author:              Gil Mizrahi
+maintainer:          gilmi@posteo.net
+copyright:           2022 Gil Mizrahi
+category:            Web
+build-type:          Simple
+cabal-version:       >=1.10
+extra-source-files:  readme.md
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Bulletin
+
+  ghc-options:         -Wall -fno-warn-type-defaults
+  default-language:    Haskell2010
+  build-depends:       base >= 4.7 && < 5
+                     , text >= 2
+                     , containers
+                     , time
+                     , stm
+                     , twain >= 2.1.0.0
+                     , warp
+                     , wai-extra
+                     , lucid
+
+executable bulletin-app
+  hs-source-dirs:      app
+  main-is:             Main.hs
+  default-language:    Haskell2010
+  ghc-options: -Wall -static -optl-static -optl-pthread -fPIC -O -threaded -rtsopts -with-rtsopts=-N
+  build-depends:       base >= 4.7 && < 5
+                     , twain-bulletin-app