diff --git a/.devcontainer.dockerfile b/.devcontainer.dockerfile
new file mode 100644
index 000000000..d0bc59da1
--- /dev/null
+++ b/.devcontainer.dockerfile
@@ -0,0 +1,40 @@
+FROM ubuntu:20.04
+
+USER root
+
+# Configure apt and install packages
+RUN apt-get update \
+    && apt-get -y install \
+        apt-utils \
+        git \
+        curl \
+        xz-utils
+
+# Install Nix
+RUN addgroup --system nixbld \
+  && adduser root nixbld \
+  && for i in $(seq 1 30); do useradd -ms /bin/bash nixbld$i &&  adduser nixbld$i nixbld; done \
+  && mkdir -m 0755 /nix && chown root /nix \
+  && mkdir -p /etc/nix \
+  && echo 'sandbox = false' > /etc/nix/nix.conf \
+  && echo 'substituters = https://cache.nixos.org https://hydra.iohk.io' >> /etc/nix/nix.conf \
+  && echo 'trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=' >> /etc/nix/nix.conf
+
+# Install Nix
+CMD /bin/bash -l
+USER root
+ENV USER root
+WORKDIR /home/root
+
+RUN touch .bash_profile \
+ && curl https://nixos.org/releases/nix/nix-2.3.8/install | sh
+
+RUN echo '. /root/.nix-profile/etc/profile.d/nix.sh' >> /root/.bashrc
+
+RUN mkdir suppoort
+COPY nix nix
+COPY support/fp-course.cabal support/cabal.project support/
+
+RUN . /root/.nix-profile/etc/profile.d/nix.sh \
+  && nix-env -f nix/shell.nix -iA buildInputs \
+  && nix-env -f nix/shell.nix -iA nativeBuildInputs
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 000000000..4d2e7a619
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,11 @@
+{
+    "name": "Functional Programming Course",
+    "dockerFile": "../.devcontainer.dockerfile",
+    "userEnvProbe": "loginShell",
+    "extensions": [
+        "haskell.haskell"
+    ],
+    "settings": {
+        "terminal.integrated.shell.linux": "/bin/bash"
+    },
+}
diff --git a/.gitignore b/.gitignore
index 14aaafe81..7d90587e9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,3 +40,12 @@ ops/*.retry
 
 # nix
 result
+
+# Files in support sub dir
+/cabal.project
+/Setup.hs
+/fp-course.cabal
+/shell.nix
+/stack.yaml
+/stack.yaml.lock
+/hie.yaml
diff --git a/.gitpod.dockerfile b/.gitpod.dockerfile
new file mode 100644
index 000000000..2016ab310
--- /dev/null
+++ b/.gitpod.dockerfile
@@ -0,0 +1,29 @@
+FROM gitpod/workspace-full
+
+USER root
+
+# Install Nix
+RUN addgroup --system nixbld \
+  && adduser gitpod nixbld \
+  && for i in $(seq 1 30); do useradd -ms /bin/bash nixbld$i &&  adduser nixbld$i nixbld; done \
+  && mkdir -m 0755 /nix && chown gitpod /nix \
+  && mkdir -p /etc/nix \
+  && echo 'sandbox = false' > /etc/nix/nix.conf \
+  && echo 'substituters = https://cache.nixos.org https://hydra.iohk.io' >> /etc/nix/nix.conf \
+  && echo 'trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=' >> /etc/nix/nix.conf
+
+# Install Nix
+CMD /bin/bash -l
+USER gitpod
+ENV USER gitpod
+WORKDIR /home/gitpod
+
+RUN touch .bash_profile \
+ && curl https://nixos.org/releases/nix/nix-2.3.8/install | sh 
+
+COPY nix nix
+COPY support/fp-course.cabal support/cabal.project support/
+
+RUN . /home/gitpod/.nix-profile/etc/profile.d/nix.sh \
+  && nix-env -f nix/shell.nix -iA buildInputs \
+  && nix-env -f nix/shell.nix -iA nativeBuildInputs
diff --git a/.gitpod.yml b/.gitpod.yml
new file mode 100644
index 000000000..bbee9e997
--- /dev/null
+++ b/.gitpod.yml
@@ -0,0 +1,12 @@
+image:
+    file: .gitpod.dockerfile
+
+vscode:
+  extensions:
+    - justusadam.language-haskell@3.3.0:uqgpHstOoamig+7LyFNNVw==
+    - haskell.haskell@1.2.0:ZPrUKYpwCCFQf9Q0phszuQ==
+
+tasks:
+- init: >
+    cd /workspace/fp-course &&
+    cp support/fp-course.cabal support/cabal.project support/hie.yaml .
diff --git a/nix/default.nix b/nix/default.nix
new file mode 100644
index 000000000..ec614edb3
--- /dev/null
+++ b/nix/default.nix
@@ -0,0 +1,20 @@
+let
+  sources = import ./sources.nix {};
+  haskellNix = import sources.haskellNix {};
+  pkgs = import
+    haskellNix.sources.nixpkgs-unstable
+    haskellNix.nixpkgsArgs;
+  # 'cleanGit' cleans a source directory based on the files known by git
+  cleanSrc = pkgs.haskell-nix.haskellLib.cleanGit {
+    name = "fp-course";
+    src = ./..;
+  };
+in pkgs.haskell-nix.cabalProject {
+  src = pkgs.haskell-nix.haskellLib.cleanSourceWith {
+    name = "fp-course";
+    src = ./..;
+    subDir = "support";
+    # filter = path: type: path == toString ./fp-course.cabal || cleanSrc.filter path type;
+  };
+  compiler-nix-name = "ghc8104";
+}
diff --git a/nix/nixpkgs.nix b/nix/nixpkgs.nix
deleted file mode 100644
index ec78d09f6..000000000
--- a/nix/nixpkgs.nix
+++ /dev/null
@@ -1,7 +0,0 @@
-import (builtins.fetchGit {
-  # Descriptive name to make the store path easier to identify
-  name = "nixos-unstable-2019-04-08";
-  url = https://github.com/nixos/nixpkgs/;
-  # `git ls-remote https://github.com/nixos/nixpkgs-channels nixos-unstable`
-  rev = "acbdaa569f4ee387386ebe1b9e60b9f95b4ab21b";
-}) {}
diff --git a/nix/shell.nix b/nix/shell.nix
new file mode 100644
index 000000000..6624a6ed4
--- /dev/null
+++ b/nix/shell.nix
@@ -0,0 +1,6 @@
+(import ./default.nix).shellFor {
+  tools = {
+    cabal = "3.2.0.0";
+    haskell-language-server = "latest";
+  };
+}
diff --git a/nix/sources.json b/nix/sources.json
new file mode 100644
index 000000000..37a7f72fc
--- /dev/null
+++ b/nix/sources.json
@@ -0,0 +1,38 @@
+{
+    "haskellNix": {
+        "branch": "master",
+        "description": "Alternative Haskell Infrastructure for Nixpkgs",
+        "homepage": "https://input-output-hk.github.io/haskell.nix",
+        "owner": "input-output-hk",
+        "repo": "haskell.nix",
+        "rev": "c4e5aea19b2436670524a230a0e5e959c8923fd1",
+        "sha256": "1inazhnsawbx6frk6jw9b9gjiybjwf5y7zix3mjri95k58l5p8i7",
+        "type": "tarball",
+        "url": "https://github.com/input-output-hk/haskell.nix/archive/c4e5aea19b2436670524a230a0e5e959c8923fd1.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": "ba57d5a29b4e0f2085917010380ef3ddc3cf380f",
+        "sha256": "1kpsvc53x821cmjg1khvp1nz7906gczq8mp83664cr15h94sh8i4",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/ba57d5a29b4e0f2085917010380ef3ddc3cf380f.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "release-20.03",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "eb86687de94beec0365e7679f27eb6c044240967",
+        "sha256": "1c3rbadv4m6cgpzl6mbnmhj7rzam3629bmsrc1yjimwc9izirz4n",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/eb86687de94beec0365e7679f27eb6c044240967.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 000000000..1938409dd
--- /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/support/copy-tool-files.bat b/support/copy-tool-files.bat
index 5cfd44078..18ed453e4 100644
--- a/support/copy-tool-files.bat
+++ b/support/copy-tool-files.bat
@@ -5,3 +5,4 @@ copy support/fp-course.cabal fp-course.cabal
 copy support/shell.nix shell.nix
 copy support/stack.yaml stack.yaml
 copy support/stack.yaml.lock stack.yaml.lock
+copy support/hie.yaml hie.yaml
diff --git a/support/copy-tool-files.sh b/support/copy-tool-files.sh
index fe1a046dc..93b50b901 100755
--- a/support/copy-tool-files.sh
+++ b/support/copy-tool-files.sh
@@ -12,3 +12,4 @@ cp -vf support/fp-course.cabal fp-course.cabal
 cp -vf support/shell.nix shell.nix
 cp -vf support/stack.yaml stack.yaml
 cp -vf support/stack.yaml.lock stack.yaml.lock
+cp -vf support/hie.yaml hie.yaml
diff --git a/support/hie.yaml b/support/hie.yaml
new file mode 100644
index 000000000..ac93f0e72
--- /dev/null
+++ b/support/hie.yaml
@@ -0,0 +1,4 @@
+cradle:
+  cabal:
+  - path: ./src
+    component: "lib:fp-course"
diff --git a/support/shell.nix b/support/shell.nix
index af2b9072f..caff26c8d 100644
--- a/support/shell.nix
+++ b/support/shell.nix
@@ -1,9 +1 @@
-{ nixpkgs ? import ./nix/nixpkgs.nix
-, compiler ? "default"
-}:
-let
-  inherit (nixpkgs) pkgs;
-in
-pkgs.mkShell {
-  buildInputs = with pkgs.haskellPackages; [ ghc ghcid ];
-}
+import nix/shell.nix