Add timeline packages

.gitignore

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+.vscode/
+.direnv/
+.envrc
+result

CHANGELOG.md

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+# Changelog
+
+## 0.1.0.0
+- Open source the timeline library we use internally at Bellroy

LICENSE

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+Copyright (C) 2023 Bellroy Pty Ltd
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. 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.
+
+3. Neither the name of the copyright holder nor the names of its
+   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
+HOLDER 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.

README.md

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 # timeline
 
-Provides a container type `Timeline a` for handling data that changes over time.
+## Motivation
+
+The world is always changing, and often we want to manage the changes of data
+using computers. Below are some concrete examples:
+
+- Employee data such as compensation, city, tax rule, time-off, etc.
+- Prices of products. A product could have different prices on Amazon and EBay,
+  and in different currencies.
+
+Timeline data is often implemented by attaching extra fields to your business
+object, denoting the start and end time of each interval. However, only
+representing and storing the data is not sufficient, we need to run operations
+on timeline data, like extracting a single data point at some specific time,
+merging multiple timelines together, etc.
+
+If you have a similar use case and don't want to reinvent the wheel, this
+library is for you.
+
+## Package Organization
+
+- `timeline` essential types and functions
+- `timeline-tests` unit tests
+- `timeline-hedgehog` hedgehog generators for timeline types
+
+## Getting Started
+
+The core type is `Timeline a`, refer to
+[Haddock](https://hackage.haskell.org/package/timeline-0.0.1.0/docs/Data-Timeline.html)
+for its usage.
+
+## Contribution
+Bellroy actively maintains this project. Feel free to submit issues and
+pull requests!
+
+The code is formatted with [`ormolu`](https://hackage.haskell.org/package/ormolu)
+
+If you use Nix:
+- `nix develop` enter a shell with all necessary tools
+- `nix build` build and run tests on all GHC versions we support
+- Use `nix flake show` to view a full list of outputs

cabal.project

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+packages: ./
+tests: True

flake.nix

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+{
+  # Use 'nix flake show' to discover the structure of the output.
+  # Multiple versions of compiler is supported.
+  inputs = {
+    nixpkgs.url = "nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
+  };
+
+  outputs = inputs:
+    let
+      cabalPackages = [
+        {
+          name = "timeline";
+          path = ./package.nix;
+        }
+      ];
+      supportedCompilers = [ "ghc8107" "ghc926" "ghc944" ];
+      defaultCompiler = "ghc926";
+    in
+    inputs.flake-utils.lib.eachDefaultSystem (system:
+      let
+        nixpkgs = import inputs.nixpkgs { inherit system; };
+
+        makePackageSet = haskellPackages: haskellPackages.override {
+          overrides = final: prev: with nixpkgs.haskell.lib;
+            builtins.listToAttrs
+              (
+                builtins.map
+                  (cabalPackage: {
+                    name = cabalPackage.name;
+                    value = prev.callPackage cabalPackage.path { };
+                  })
+                  cabalPackages
+              );
+        };
+
+        essentialTools = with nixpkgs; [
+          cabal-install
+          hlint
+          ormolu
+          haskellPackages.cabal-fmt
+          cabal2nix
+          miniserve
+        ];
+
+        makeShell = haskellPackages: (makePackageSet haskellPackages).shellFor {
+          packages = p: builtins.map (cabalPackage: p.${cabalPackage.name}) cabalPackages;
+          withHoogle = true;
+          buildInputs = essentialTools ++ [
+            nixpkgs.haskellPackages.haskell-language-server
+          ];
+        };
+
+        lightShell = nixpkgs.mkShell {
+          packages = essentialTools ++ [ nixpkgs.ghc ];
+        };
+      in
+      {
+        packages =
+          let packagesWithoutDefault =
+            builtins.listToAttrs
+              (
+                builtins.concatMap
+                  (compilerName:
+                    let pkgSet = makePackageSet nixpkgs.haskell.packages.${compilerName};
+                    in
+                    builtins.map
+                      (cabalPackage: {
+                        name = "${compilerName}-${cabalPackage.name}";
+                        value = pkgSet.${cabalPackage.name};
+                      })
+                      cabalPackages
+                  )
+                  supportedCompilers
+              );
+          in
+          packagesWithoutDefault // {
+            default = nixpkgs.runCommand "aggregate"
+              {
+                buildInputs = builtins.map (name: packagesWithoutDefault.${name})
+                  (builtins.attrNames packagesWithoutDefault);
+              } "touch $out";
+          };
+
+        devShells =
+          let devShellsWithoutDefault =
+            builtins.listToAttrs
+              (
+                builtins.map
+                  (compilerName: {
+                    name = compilerName;
+                    value = makeShell nixpkgs.haskell.packages.${compilerName};
+                  })
+                  supportedCompilers
+              ); in
+          devShellsWithoutDefault // {
+            default = devShellsWithoutDefault.${defaultCompiler};
+            light = lightShell;
+          };
+      }
+    );
+}

package.nix

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+{ mkDerivation, base, bytestring, containers, hashable, hedgehog
+, indexed-traversable, lib, semigroupoids, tasty, tasty-discover
+, tasty-golden, tasty-hedgehog, tasty-hunit, template-haskell, text
+, th-compat, time, transformers
+}:
+mkDerivation {
+  pname = "timeline";
+  version = "0.1.0.0";
+  src = ./.;
+  libraryHaskellDepends = [
+    base containers hedgehog indexed-traversable semigroupoids
+    template-haskell text th-compat time
+  ];
+  testHaskellDepends = [
+    base bytestring containers hashable hedgehog indexed-traversable
+    tasty tasty-golden tasty-hedgehog tasty-hunit text time
+    transformers
+  ];
+  testToolDepends = [ tasty-discover ];
+  description = "Data type representing a piecewise-constant function over time";
+  license = lib.licenses.bsd3;
+}