diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..051d09d
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+eval "$(lorri direnv)"
diff --git a/.github/CODE_OF_CONDUCT.md b/.github/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..1726608
--- /dev/null
+++ b/.github/CODE_OF_CONDUCT.md
@@ -0,0 +1,85 @@
+# Code of Conduct
+
+## 1. Purpose
+
+A primary goal of Witchcrafters is to be inclusive to the largest number of contributors, with the most varied and diverse backgrounds possible. As such, we are committed to providing a friendly, safe and welcoming environment for all, regardless of gender, sexual orientation, ability, ethnicity, socioeconomic status, and religion (or lack thereof).
+
+This code of conduct outlines our expectations for all those who participate in our community, as well as the consequences for unacceptable behavior.
+
+We invite all those who participate in Witchcrafters to help us create safe and positive experiences for everyone.
+
+## 2. Open Source Citizenship
+
+A supplemental goal of this Code of Conduct is to increase open source citizenship by encouraging participants to recognize and strengthen the relationships between our actions and their effects on our community.
+
+Communities mirror the societies in which they exist and positive action is essential to counteract the many forms of inequality and abuses of power that exist in society.
+
+If you see someone who is making an extra effort to ensure our community is welcoming, friendly, and encourages all participants to contribute to the fullest extent, we want to know.
+
+## 3. Expected Behavior
+
+The following behaviors are expected and requested of all community members:
+
+*   Participate in an authentic and active way. In doing so, you contribute to the health and longevity of this community.
+*   Exercise consideration and respect in your speech and actions.
+*   Attempt collaboration before conflict.
+*   Refrain from demeaning, discriminatory, or harassing behavior and speech.
+*   Be mindful of your surroundings and of your fellow participants. Alert community leaders if you notice a dangerous situation, someone in distress, or violations of this Code of Conduct, even if they seem inconsequential.
+*   Remember that community event venues may be shared with members of the public; please be respectful to all patrons of these locations.
+
+## 4. Unacceptable Behavior
+
+The following behaviors are considered harassment and are unacceptable within our community:
+
+*   Violence, threats of violence or violent language directed against another person.
+*   Sexist, racist, homophobic, transphobic, ableist or otherwise discriminatory jokes and language.
+*   Posting or displaying sexually explicit or violent material.
+*   Posting or threatening to post other people’s personally identifying information ("doxing").
+*   Personal insults, particularly those related to gender, sexual orientation, race, religion, or disability.
+*   Inappropriate photography or recording.
+*   Inappropriate physical contact. You should have someone’s consent before touching them.
+*   Unwelcome sexual attention. This includes, sexualized comments or jokes; inappropriate touching, groping, and unwelcomed sexual advances.
+*   Deliberate intimidation, stalking or following (online or in person).
+*   Advocating for, or encouraging, any of the above behavior.
+*   Sustained disruption of community events, including talks and presentations.
+
+## 5. Consequences of Unacceptable Behavior
+
+Unacceptable behavior from any community member, including sponsors and those with decision-making authority, will not be tolerated.
+
+Anyone asked to stop unacceptable behavior is expected to comply immediately.
+
+If a community member engages in unacceptable behavior, the community organizers may take any action they deem appropriate, up to and including a temporary ban or permanent expulsion from the community without warning (and without refund in the case of a paid event).
+
+## 6. Reporting Guidelines
+
+If you are subject to or witness unacceptable behavior, or have any other concerns, please notify a community organizer as soon as possible. hello@brooklynzelenka.com.
+
+
+
+Additionally, community organizers are available to help community members engage with local law enforcement or to otherwise help those experiencing unacceptable behavior feel safe. In the context of in-person events, organizers will also provide escorts as desired by the person experiencing distress.
+
+## 7. Addressing Grievances
+
+If you feel you have been falsely or unfairly accused of violating this Code of Conduct, you should notify the maintainers with a concise description of your grievance. Your grievance will be handled in accordance with our existing governing policies.
+
+
+
+## 8. Scope
+
+We expect all community participants (contributors, paid or otherwise; sponsors; and other guests) to abide by this Code of Conduct in all community venues–online and in-person–as well as in all one-on-one communications pertaining to community business.
+
+This code of conduct and its related procedures also applies to unacceptable behavior occurring outside the scope of community activities when such behavior has the potential to adversely affect the safety and well-being of community members.
+
+## 9. Contact info
+
+hello@fission.codes
+
+## 10. License and attribution
+
+This Code of Conduct is distributed under a [Creative Commons Attribution-ShareAlike license](http://creativecommons.org/licenses/by-sa/3.0/).
+
+Portions of text derived from the [Django Code of Conduct](https://www.djangoproject.com/conduct/) and the [Geek Feminism Anti-Harassment Policy](http://geekfeminism.wikia.com/wiki/Conference_anti-harassment/Policy).
+
+Retrieved on November 22, 2016 from [http://citizencodeofconduct.org/](http://citizencodeofconduct.org/)
+
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..8151cf0
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,40 @@
+A similar PR may already be submitted!
+Please search among the [Pull request](../) before creating one.
+
+Thanks for submitting a pull request! Please provide enough information so that others can review your pull request:
+
+For more information, see the `CONTRIBUTING` guide.
+
+
+## Summary
+<!-- Summary of the PR -->
+
+This PR fixes/implements the following **bugs/features**
+
+* [ ] Bug 1
+* [ ] Bug 2
+* [ ] Feature 1
+* [ ] Feature 2
+* [ ] Breaking changes
+
+<!-- You can skip this if you're fixing a typo or adding an app to the Showcase. -->
+
+Explain the **motivation** for making this change. What existing problem does the pull request solve?
+
+<!-- Example: When "Adding a function to do X", explain why it is necessary to have a way to do X. -->
+
+## Test plan (required)
+
+Demonstrate the code is solid. Example: The exact commands you ran and their output, screenshots / videos if the pull request changes UI.
+
+<!-- Make sure tests pass on Circle CI. -->
+
+
+## Closing issues
+
+<!-- Put `closes #XXXX` in your comment to auto-close the issue that your PR fixes (if such). -->
+Fixes #
+
+## After Merge
+* [ ] Does this change invalidate any docs or tutorials? _If so ensure the changes needed are either made or recorded_
+* [ ] Does this change require a release to be made? Is so please create and deploy the release
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
new file mode 100644
index 0000000..fb4fd10
--- /dev/null
+++ b/.github/workflows/ci.yaml
@@ -0,0 +1,21 @@
+on:
+  push:         { "branches": [ "main" ] }
+  pull_request: { "branches": [ "main" ] }
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    name: OTP ${{matrix.otp}} / Elixir ${{matrix.elixir}}
+    strategy:
+      matrix:
+        otp: ['23.0']
+        elixir: ['1.11.3']
+    steps:
+      - uses: actions/checkout@v2
+      - uses: erlef/setup-elixir@v1
+        with:
+          otp-version: ${{matrix.otp}}
+          elixir-version: ${{matrix.elixir}}
+      - run: MIX_ENV=test mix deps.get
+      - run: MIX_ENV=test mix test
+      - run: MIX_ENV=test mix credo --strict
diff --git a/.github/workflows/greetings.yml b/.github/workflows/greetings.yml
new file mode 100644
index 0000000..42626cd
--- /dev/null
+++ b/.github/workflows/greetings.yml
@@ -0,0 +1,13 @@
+name: Greetings
+
+on: [pull_request, issues]
+
+jobs:
+  greeting:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/first-interaction@v1
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        issue-message: 'Thank you for submitting an issue! It means a lot that you took the time -- it helps us be better 🙏'
+        pr-message: "Thank you for submitting a PR 🎉 It's very appreciated!"
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 77c2939..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,8 +0,0 @@
-language: elixir
-elixir:
-  - 1.7.0
-otp_release:
-  - 20.0
-script: mix test; mix credo --strict
-after_script:
-  - MIX_ENV=docs mix do deps.get, inch.report
diff --git a/mix.exs b/mix.exs
index 3f92795..ce74433 100644
--- a/mix.exs
+++ b/mix.exs
@@ -8,7 +8,7 @@ defmodule Algae.Mixfile do
       deps: deps(),
 
       # Versions
-      version: "1.2.4",
+      version: "1.2.5",
       elixir: "~> 1.9",
 
       # Docs
@@ -23,20 +23,24 @@ defmodule Algae.Mixfile do
 
   defp aliases do
     [
-      quality: ["test", "credo --strict"]
+      quality: [
+          "test",
+          "credo --strict"
+        ]
     ]
   end
 
   defp deps do
     [
-      {:credo, "~> 1.1", only: [:dev, :test]},
-      {:dialyxir, "~> 0.5", only: :dev},
-      {:earmark, "~> 1.4.0", only: :dev},
-      {:ex_doc, "~> 0.21.2", only: :dev},
-      {:inch_ex, "~> 2.0", only: [:dev, :docs, :test]},
-      {:quark, "~> 2.3"},
-      {:type_class, "~> 1.2"},
-      {:witchcraft, "~> 1.0"}
+      {:credo,       "~> 1.5",  only: [:dev, :test],        runtime: false},
+      {:inch_ex,     "~> 2.0",  only: [:dev, :docs, :test], runtime: false},
+      {:dialyxir,    "~> 1.1",  only: :dev,                 runtime: false},
+      {:earmark,     "~> 1.4",  only: :dev,                 runtime: false},
+      {:ex_doc,      "~> 0.23", only: :dev,                 runtime: false},
+
+      {:quark,       "~> 2.2"},
+      {:type_class,  "~> 1.2"},
+      {:witchcraft,  "~> 1.0"},
     ]
   end
 
@@ -51,7 +55,7 @@ defmodule Algae.Mixfile do
 
   defp package do
     [
-      licenses: ["MIT"],
+      licenses: ["Apache-2.0"],
       links: %{"GitHub" => "https://github.com/witchcrafters/algae"},
       maintainers: ["Brooklyn Zelenka", "Steven Vandevelde"]
     ]
diff --git a/mix.lock b/mix.lock
deleted file mode 100644
index c0a867c..0000000
--- a/mix.lock
+++ /dev/null
@@ -1,18 +0,0 @@
-%{
-  "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm"},
-  "credo": {:hex, :credo, "1.1.4", "c2f3b73c895d81d859cec7fcee7ffdb972c595fd8e85ab6f8c2adbf01cf7c29c", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm"},
-  "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], [], "hexpm"},
-  "earmark": {:hex, :earmark, "1.4.0", "397e750b879df18198afc66505ca87ecf6a96645545585899f6185178433cc09", [:mix], [], "hexpm"},
-  "ex_doc": {:hex, :ex_doc, "0.21.2", "caca5bc28ed7b3bdc0b662f8afe2bee1eedb5c3cf7b322feeeb7c6ebbde089d6", [:mix], [{:earmark, "~> 1.3.3 or ~> 1.4", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
-  "exceptional": {:hex, :exceptional, "2.1.1", "f18f8c1be63aab7fe8f3000cf2a8678936544fc39af1e2bc4a5c3c9e38cd8899", [:mix], [], "hexpm"},
-  "inch_ex": {:hex, :inch_ex, "2.0.0", "24268a9284a1751f2ceda569cd978e1fa394c977c45c331bb52a405de544f4de", [:mix], [{:bunt, "~> 0.2", [hex: :bunt, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm"},
-  "jason": {:hex, :jason, "1.1.2", "b03dedea67a99223a2eaf9f1264ce37154564de899fd3d8b9a21b1a6fd64afe7", [:mix], [{:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm"},
-  "makeup": {:hex, :makeup, "1.0.0", "671df94cf5a594b739ce03b0d0316aa64312cee2574b6a44becb83cd90fb05dc", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.14.0", "cf8b7c66ad1cff4c14679698d532f0b5d45a3968ffbcbfd590339cb57742f1ae", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
-  "nimble_parsec": {:hex, :nimble_parsec, "0.5.1", "c90796ecee0289dbb5ad16d3ad06f957b0cd1199769641c961cfe0b97db190e0", [:mix], [], "hexpm"},
-  "operator": {:hex, :operator, "0.2.0", "b613bdb520a20dbc016d921d444fd2ef2212136be9385d6dca448a2a38d0577f", [:mix], [], "hexpm"},
-  "poison": {:hex, :poison, "3.1.0", "d9eb636610e096f86f25d9a46f35a9facac35609a7591b3be3326e99a0484665", [:mix], [], "hexpm"},
-  "quark": {:hex, :quark, "2.3.0", "3742ddc14441b4930c7067741879cb5b3e4881f391ea0aed7b138f20d16b30bb", [:mix], [], "hexpm"},
-  "type_class": {:hex, :type_class, "1.2.5", "b972bb22202e801d83e8670228d9a1476cd2c9fc7da00b7039b19d6d06b17905", [:mix], [{:exceptional, "~> 2.1", [hex: :exceptional, repo: "hexpm", optional: false]}], "hexpm"},
-  "witchcraft": {:hex, :witchcraft, "1.0.1", "5db4f9f92be480958a51bee01d3fd283a707576e5e0a0810d4442eac1f47e395", [:mix], [{:exceptional, "~> 2.1", [hex: :exceptional, repo: "hexpm", optional: false]}, {:operator, "~> 0.2", [hex: :operator, repo: "hexpm", optional: false]}, {:quark, "~> 2.2", [hex: :quark, repo: "hexpm", optional: false]}, {:type_class, "~> 1.2", [hex: :type_class, repo: "hexpm", optional: false]}], "hexpm"},
-}
diff --git a/nix/commands.nix b/nix/commands.nix
new file mode 100644
index 0000000..5499478
--- /dev/null
+++ b/nix/commands.nix
@@ -0,0 +1,87 @@
+{ pkgs, unstable, ... }:
+  let
+    bash    = "${pkgs.bash}/bin/bash";
+    figlet  = "${pkgs.figlet}/bin/figlet";
+    lolcat  = "${pkgs.lolcat}/bin/lolcat";
+    mix     = "${unstable.elixir}/bin/mix";
+
+    cmd = description: script:
+      { inherit description;
+        inherit script;
+      };
+
+    command = {name, script, description ? "<No description given>"}:
+      let
+        package =
+          pkgs.writeScriptBin name ''
+            #!${bash}
+            echo "⚙️  Running ${name}..."
+            ${script}
+          '';
+
+        bin = "${package}/bin/${name}";
+      in
+         { package     = package;
+           description = description;
+           bin         = bin;
+         };
+
+    commands = defs:
+      let
+        names =
+          builtins.attrNames defs;
+
+        helper =
+          let
+            lengths = map builtins.stringLength names;
+            maxLen  = builtins.foldl' (acc: x: if x > acc then x else acc) 0 lengths;
+            maxPad  =
+              let
+                go = acc:
+                  if builtins.stringLength acc >= maxLen
+                  then acc
+                  else go (" " + acc);
+              in
+                go "";
+
+            folder = acc: name:
+              let
+                nameLen = builtins.stringLength name;
+                padLen  = maxLen - nameLen;
+                padding = builtins.substring 0 padLen maxPad;
+              in
+                acc + " && echo '${name} ${padding}| ${(builtins.getAttr name defs).description}'";
+
+            lines =
+              builtins.foldl' folder "echo ''" names;
+
+          in
+            pkgs.writeScriptBin "helpme" ''
+              #!${pkgs.stdenv.shell}
+              ${pkgs.figlet}/bin/figlet "Commands" | ${pkgs.lolcat}/bin/lolcat
+              ${toString lines}
+            '';
+
+        mapper = name:
+          let
+            element =
+              builtins.getAttr name defs;
+
+            task = command {
+              inherit name;
+              description = element.description;
+              script      = element.script;
+            };
+          in
+            task.package;
+
+        packages =
+          map mapper names;
+
+      in
+        [helper] ++ packages;
+
+  in
+    commands {
+      quality = cmd "Run all tests, linters, and so on" "MIX_ENV=test ${mix} quality";
+    }
diff --git a/nix/sources.json b/nix/sources.json
new file mode 100644
index 0000000..189720c
--- /dev/null
+++ b/nix/sources.json
@@ -0,0 +1,50 @@
+{
+    "darwin": {
+        "branch": "nixpkgs-20.09-darwin",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e716ddfac4be879ffbae75c3914a538dd5d4d12e",
+        "sha256": "0c2090sz4nvd1bqa9bfz3b6mj0q8b7v4jzgsykn2hf291l3h94d6",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/e716ddfac4be879ffbae75c3914a538dd5d4d12e.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "niv": {
+        "branch": "master",
+        "description": "Easy dependency management for Nix projects",
+        "homepage": "https://github.com/nmattia/niv",
+        "owner": "nmattia",
+        "repo": "niv",
+        "rev": "af958e8057f345ee1aca714c1247ef3ba1c15f5e",
+        "sha256": "1qjavxabbrsh73yck5dcq8jggvh3r2jkbr6b5nlz5d9yrqm9255n",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/af958e8057f345ee1aca714c1247ef3ba1c15f5e.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "nixos-20.09",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "60b18a066e8ce5dd21ebff5324345d3586a67ad9",
+        "sha256": "1cr7r16vb4nxifykhak8awspdpr775kafrl7p6asgwicsng7giya",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/60b18a066e8ce5dd21ebff5324345d3586a67ad9.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "unstable": {
+        "branch": "nixpkgs-unstable",
+        "description": "Nix Packages collection",
+        "homepage": null,
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "c5147860e23ed75ce9d40298c66b416c00be1167",
+        "sha256": "104mw4rfbzyrfkxq468dlk38drrjx92dgyvkazgci67a6cx3n6nx",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/c5147860e23ed75ce9d40298c66b416c00be1167.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}
diff --git a/nix/sources.nix b/nix/sources.nix
new file mode 100644
index 0000000..1938409
--- /dev/null
+++ b/nix/sources.nix
@@ -0,0 +1,174 @@
+# This file has been generated by Niv.
+
+let
+
+  #
+  # The fetchers. fetch_<type> fetches specs of type <type>.
+  #
+
+  fetch_file = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchurl { inherit (spec) url sha256; name = name'; }
+      else
+        pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
+
+  fetch_tarball = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
+      else
+        pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
+
+  fetch_git = name: spec:
+    let
+      ref =
+        if spec ? ref then spec.ref else
+          if spec ? branch then "refs/heads/${spec.branch}" else
+            if spec ? tag then "refs/tags/${spec.tag}" else
+              abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
+    in
+      builtins.fetchGit { url = spec.repo; inherit (spec) rev; inherit ref; };
+
+  fetch_local = spec: spec.path;
+
+  fetch_builtin-tarball = name: throw
+    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=tarball -a builtin=true'';
+
+  fetch_builtin-url = name: throw
+    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=file -a builtin=true'';
+
+  #
+  # Various helpers
+  #
+
+  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
+  sanitizeName = name:
+    (
+      concatMapStrings (s: if builtins.isList s then "-" else s)
+        (
+          builtins.split "[^[:alnum:]+._?=-]+"
+            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
+        )
+    );
+
+  # The set of packages used when specs are fetched using non-builtins.
+  mkPkgs = sources: system:
+    let
+      sourcesNixpkgs =
+        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
+      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
+      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
+    in
+      if builtins.hasAttr "nixpkgs" sources
+      then sourcesNixpkgs
+      else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
+        import <nixpkgs> {}
+      else
+        abort
+          ''
+            Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
+            add a package called "nixpkgs" to your sources.json.
+          '';
+
+  # The actual fetching function.
+  fetch = pkgs: name: spec:
+
+    if ! builtins.hasAttr "type" spec then
+      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
+    else if spec.type == "file" then fetch_file pkgs name spec
+    else if spec.type == "tarball" then fetch_tarball pkgs name spec
+    else if spec.type == "git" then fetch_git name spec
+    else if spec.type == "local" then fetch_local spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
+    else if spec.type == "builtin-url" then fetch_builtin-url name
+    else
+      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
+
+  # If the environment variable NIV_OVERRIDE_${name} is set, then use
+  # the path directly as opposed to the fetched source.
+  replace = name: drv:
+    let
+      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
+      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
+    in
+      if ersatz == "" then drv else
+        # this turns the string into an actual Nix path (for both absolute and
+        # relative paths)
+        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
+
+  # Ports of functions for older nix versions
+
+  # a Nix version of mapAttrs if the built-in doesn't exist
+  mapAttrs = builtins.mapAttrs or (
+    f: set: with builtins;
+    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
+  );
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
+  range = first: last: if first > last then [] else builtins.genList (n: first + n) (last - first + 1);
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
+  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
+  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
+  concatMapStrings = f: list: concatStrings (map f list);
+  concatStrings = builtins.concatStringsSep "";
+
+  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
+  optionalAttrs = cond: as: if cond then as else {};
+
+  # fetchTarball version that is compatible between all the versions of Nix
+  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchTarball;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchTarball ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchTarball attrs;
+
+  # fetchurl version that is compatible between all the versions of Nix
+  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchurl;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchurl ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchurl attrs;
+
+  # Create the final "sources" from the config
+  mkSources = config:
+    mapAttrs (
+      name: spec:
+        if builtins.hasAttr "outPath" spec
+        then abort
+          "The values in sources.json should not have an 'outPath' attribute"
+        else
+          spec // { outPath = replace name (fetch config.pkgs name spec); }
+    ) config.sources;
+
+  # The "config" used by the fetchers
+  mkConfig =
+    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
+    , sources ? if isNull sourcesFile then {} else builtins.fromJSON (builtins.readFile sourcesFile)
+    , system ? builtins.currentSystem
+    , pkgs ? mkPkgs sources system
+    }: rec {
+      # The sources, i.e. the attribute set of spec name to spec
+      inherit sources;
+
+      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
+      inherit pkgs;
+    };
+
+in
+mkSources (mkConfig {}) // { __functor = _: settings: mkSources (mkConfig settings); }
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..e83ccc7
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,45 @@
+ let
+  sources  = import ./nix/sources.nix;
+  commands = import ./nix/commands.nix;
+
+  nixos    = import sources.nixpkgs  {};
+  darwin   = import sources.darwin   {};
+  unstable = import sources.unstable {};
+
+  pkgs  = if darwin.stdenv.isDarwin then darwin else nixos;
+  tasks = commands {
+    inherit pkgs;
+    inherit unstable;
+  };
+
+  deps = {
+    common =
+      [  pkgs.niv
+      ];
+
+    elixir =
+      [ unstable.elixir
+      ];
+
+    platform =
+      if pkgs.stdenv.isDarwin then
+        [ unstable.darwin.apple_sdk.frameworks.CoreServices
+          unstable.darwin.apple_sdk.frameworks.Foundation
+        ]
+      else if pkgs.stdenv.isLinux then
+        [ pkgs.inotify-tools
+        ]
+      else
+        [];
+  };
+in
+
+pkgs.mkShell {
+  name = "Algae";
+  nativeBuildInputs = builtins.concatLists [
+    deps.common 
+    deps.elixir
+    deps.platform
+    tasks
+  ];
+}