diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6a0dcbcd..229b8368 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,53 +1,53 @@
 jobs:
   build:
     env:
-      SCALA_VERSION: "${{ matrix.scala }}"
-    name: "Scala ${{ matrix.scala }}, Java ${{ matrix.java }}"
+      SCALA_VERSION: ${{ matrix.scala }}
+    name: Scala ${{ matrix.scala }}, Java ${{ matrix.java }}
     runs-on: ubuntu-latest
     steps:
-      - uses: "actions/checkout@v2"
-      - uses: "actions/setup-java@v1"
-        with:
-          java-version: "${{ matrix.java }}"
-      - name: Get current week
-        run: |
-          echo "::set-env name=current_week::$(( 10#$(date +%U) ))"
-          echo "::set-env name=last_week::$(( 10#$(date +%U) - 1 ))"
-      - name: Cache SBT coursier cache
-        uses: "actions/cache@v1"
-        with:
-          key: "coursier-${{ env.current_week }}"
-          path: "~/.cache/coursier"
-          restore-keys: "coursier-${{ env.last_week }}"
-      - name: Cache SBT
-        uses: "actions/cache@v1"
-        with:
-          key: "sbt-${{ env.current_week }}"
-          path: "~/.sbt"
-          restore-keys: "sbt-${{ env.last_week }}"
-      - name: Unused and undeclared dependencies
-        run: "sbt ++$SCALA_VERSION unusedCompileDependenciesTest undeclaredCompileDependenciesTest"
-      - name: Tests
-        run: "sbt ++$SCALA_VERSION test"
-      - name: Scaladocs
-        run: "sbt ++$SCALA_VERSION doc"
-      - name: MiMa
-        run: "sbt ++$SCALA_VERSION mimaReportBinaryIssues"
-      - name: Scalafmt
-        run: "sbt ++$SCALA_VERSION scalafmtCheckAll"
-      - if: "startsWith(matrix.scala, '2.12')"
-        name: Test docs
-        run: "sbt ++$SCALA_VERSION docs/makeSite"
+    - uses: actions/checkout@v2
+    - uses: actions/setup-java@v1
+      with:
+        java-version: ${{ matrix.java }}
+    - name: Get current week
+      run: |
+        echo \"::set-env name=current_week::$(( 10#$(date +%U) ))\"
+        echo \"::set-env name=last_week::$(( 10#$(date +%U) - 1 ))\"
+    - name: Cache SBT coursier cache
+      uses: actions/cache@v1
+      with:
+        key: coursier-${{ env.current_week }}
+        path: ~/.cache/coursier
+        restore-keys: coursier-${{ env.last_week }}
+    - name: Cache SBT
+      uses: actions/cache@v1
+      with:
+        key: sbt-${{ env.current_week }}
+        path: ~/.sbt
+        restore-keys: sbt-${{ env.last_week }}
+    - name: Unused and undeclared dependencies
+      run: sbt ++$SCALA_VERSION unusedCompileDependenciesTest undeclaredCompileDependenciesTest
+    - name: Tests
+      run: sbt ++$SCALA_VERSION test
+    - name: Scaladocs
+      run: sbt ++$SCALA_VERSION doc
+    - name: MiMa
+      run: sbt ++$SCALA_VERSION mimaReportBinaryIssues
+    - name: Scalafmt
+      run: sbt ++$SCALA_VERSION scalafmtCheckAll
+    - if: startsWith(matrix.scala, '2.12')
+      name: Test docs
+      run: sbt ++$SCALA_VERSION docs/makeSite
     strategy:
       fail-fast: false
       matrix:
         java:
-          - '11'
-          - '14'
+        - '11'
+        - '14'
         scala:
-          - '2.12.11'
-          - '2.13.1'
+        - 2.12.11
+        - 2.13.1
 name: CI
-on:
-  - push
-  - pull_request
+'on':
+- push
+- pull_request
diff --git a/.github/workflows/dhall.yml b/.github/workflows/dhall.yml
index 8c83e597..d5e024e2 100644
--- a/.github/workflows/dhall.yml
+++ b/.github/workflows/dhall.yml
@@ -2,24 +2,15 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: "actions/checkout@v2"
-      - name: Setup Dhall
-        run: |
-          cd $(mktemp -d)
-          curl -L https://github.com/dhall-lang/dhall-haskell/releases/download/1.31.1/dhall-1.31.1-x86_64-linux.tar.bz2 | tar xj
-          curl -L https://github.com/dhall-lang/dhall-haskell/releases/download/1.31.1/dhall-json-1.6.3-x86_64-linux.tar.bz2 | tar xj
-          mkdir -p $HOME/bin
-          mv bin/* $HOME/bin/
-          echo "::add-path::$HOME/bin"
-      - name: Check Dhall formatting
-        run: |
-          [[ $(find -name '*.dhall' -exec sh -c 'dhall --ascii format --check < {}' \; |& wc -c) -eq 0 ]]
-      - name: Check generated YAML files
-        run: |
-          cd dhall
-          ./generateYaml.sh
-          [[ $(git status --porcelain | wc -l) -eq 0 ]]
+    - uses: actions/checkout@v2
+    - uses: actions/setup-java@v1
+      with:
+        java-version: '11'
+    - name: Check generated YAML files
+      run: |
+        sbt convertDhall
+        [[ $(git status --porcelain | wc -l) -eq 0 ]]
 name: Check Dhall configs
-on:
-  - push
-  - pull_request
+'on':
+- push
+- pull_request
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index eea53b62..470141b9 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -2,49 +2,50 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     steps:
-      - uses: "actions/checkout@v2"
-      - name: Unshallow
-        run: git fetch --unshallow
-      - uses: "actions/setup-java@v1"
-        with:
-          java-version: '11'
-      - uses: "olafurpg/setup-gpg@v2"
-      - name: Get current week
-        run: |
-          echo "::set-env name=current_week::$(( 10#$(date +%U) ))"
-          echo "::set-env name=last_week::$(( 10#$(date +%U) - 1 ))"
-      - name: Cache SBT coursier cache
-        uses: "actions/cache@v1"
-        with:
-          key: "coursier-${{ env.current_week }}"
-          path: "~/.cache/coursier"
-          restore-keys: "coursier-${{ env.last_week }}"
-      - name: Cache SBT
-        uses: "actions/cache@v1"
-        with:
-          key: "sbt-${{ env.current_week }}"
-          path: "~/.sbt"
-          restore-keys: "sbt-${{ env.last_week }}"
-      - env:
-          PGP_PASSPHRASE: "${{ secrets.PGP_PASSPHRASE }}"
-          PGP_SECRET: "${{ secrets.PGP_SECRET }}"
-          SBT_GHPAGES_COMMIT_MESSAGE: "Updated site: sha=${{ github.sha }} build=${{ github.run_id }}"
-          SONATYPE_PASSWORD: "${{ secrets.SONATYPE_PASSWORD }}"
-          SONATYPE_USERNAME: "${{ secrets.SONATYPE_USERNAME }}"
-          SSH_PRIVATE_KEY: "${{ secrets.SSH_PRIVATE_KEY }}"
-        name: Release
-        run: |
-          echo "$PGP_SECRET" | base64 --decode | gpg --import --no-tty --batch --yes
-          eval "$(ssh-agent -s)"
-          echo "$SSH_PRIVATE_KEY" | ssh-add -
-          git config --global user.name "GitHub Actions CI"
-          git config --global user.email "ghactions@invalid"
-          
-          sbt ci-release docs/makeSite docs/ghpagesPushSite
+    - uses: actions/checkout@v2
+    - name: Unshallow
+      run: git fetch --unshallow
+    - uses: actions/setup-java@v1
+      with:
+        java-version: '11'
+    - uses: olafurpg/setup-gpg@v2
+    - name: Get current week
+      run: |
+        echo \"::set-env name=current_week::$(( 10#$(date +%U) ))\"
+        echo \"::set-env name=last_week::$(( 10#$(date +%U) - 1 ))\"
+    - name: Cache SBT coursier cache
+      uses: actions/cache@v1
+      with:
+        key: coursier-${{ env.current_week }}
+        path: ~/.cache/coursier
+        restore-keys: coursier-${{ env.last_week }}
+    - name: Cache SBT
+      uses: actions/cache@v1
+      with:
+        key: sbt-${{ env.current_week }}
+        path: ~/.sbt
+        restore-keys: sbt-${{ env.last_week }}
+    - env:
+        PGP_PASSPHRASE: ${{ secrets.PGP_PASSPHRASE }}
+        PGP_SECRET: ${{ secrets.PGP_SECRET }}
+        SBT_GHPAGES_COMMIT_MESSAGE: 'Updated site: sha=${{ github.sha }} build=${{
+          github.run_id }}'
+        SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
+        SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }}
+        SSH_PRIVATE_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
+      name: Release
+      run: |
+        echo \"$PGP_SECRET\" | base64 --decode | gpg --import --no-tty --batch --yes
+        eval \"$(ssh-agent -s)\"
+        echo \"$SSH_PRIVATE_KEY\" | ssh-add -
+        git config --global user.name \"GitHub Actions CI\"
+        git config --global user.email \"ghactions@invalid\"
+
+        sbt ci-release docs/makeSite docs/ghpagesPushSite
 name: Publish releases and snapshots
-on:
+'on':
   push:
     branches:
-      - master
+    - master
     tags:
-      - "*"
+    - '*'
diff --git a/.mergify.yml b/.mergify.yml
index fdb69542..ce634439 100644
--- a/.mergify.yml
+++ b/.mergify.yml
@@ -1,12 +1,12 @@
 pull_request_rules:
-  - actions:
-      merge:
-        method: merge
-    conditions:
-      - author=scala-steward
-      - "body~=labels:.*semver-patch.*"
-      - "status-success=Scala 2.12.11, Java 11"
-      - "status-success=Scala 2.12.11, Java 14"
-      - "status-success=Scala 2.13.1, Java 11"
-      - "status-success=Scala 2.13.1, Java 14"
-    name: "automatically merge scala-steward's PRs"
+- actions:
+    merge:
+      method: merge
+  conditions:
+  - author=scala-steward
+  - body~=labels:.*semver-patch.*
+  - status-success=Scala 2.12.11, Java 11
+  - status-success=Scala 2.12.11, Java 14
+  - status-success=Scala 2.13.1, Java 11
+  - status-success=Scala 2.13.1, Java 14
+  name: automatically merge scala-steward's PRs
diff --git a/build.sbt b/build.sbt
index 81d0d4d0..067077d2 100644
--- a/build.sbt
+++ b/build.sbt
@@ -3,7 +3,8 @@ lazy val `http4s-jdk-http-client` = project
   .disablePlugins(MimaPlugin)
   .settings(commonSettings, skipOnPublishSettings)
   .settings(
-    crossScalaVersions := Nil
+    crossScalaVersions := Nil,
+    Dhall.convertDhallTask
   )
   .aggregate(core)
 
@@ -36,9 +37,6 @@ val javaWebsocketV = "1.4.1"
 val kindProjectorV = "0.10.3"
 val betterMonadicForV = "0.3.1"
 
-lazy val scalaVersions =
-  upickle.default.read[List[String]](new File("scalaVersions.json"))
-
 // format: off
 val coreDeps = Seq(
   "org.typelevel"       %% "cats-core"                  % catsV,
@@ -65,8 +63,9 @@ val coreDeps = Seq(
 // General Settings
 lazy val commonSettings = Seq(
   organization := "org.http4s",
-  scalaVersion := scalaVersions.head,
-  crossScalaVersions := scalaVersions,
+  Dhall.scalaVersionsImpl,
+  scalaVersion := Dhall.scalaVersions.value.default,
+  crossScalaVersions := Dhall.scalaVersions.value.all,
   scalacOptions += "-Yrangepos",
   scalacOptions in (Compile, doc) ++= Seq(
     "-groups",
diff --git a/dhall/ci.dhall b/dhall/ci.dhall
index 544e4ece..b5e127f7 100644
--- a/dhall/ci.dhall
+++ b/dhall/ci.dhall
@@ -24,7 +24,7 @@ let steps =
                 c.Run::{
                 , name = "Test docs"
                 , run = "docs/makeSite"
-                , if = Some "startsWith(matrix.scala, '2.12')"
+                , `if` = Some "startsWith(matrix.scala, '2.12')"
                 }
             ]
 
@@ -35,7 +35,8 @@ in  { name = "CI"
         /\  { name = c.ciJobName "\${{ matrix.scala }}" "\${{ matrix.java }}"
             , strategy =
               { fail-fast = False
-              , matrix = { java = c.javaVersions.all, scala = c.scalaVersions }
+              , matrix =
+                { java = c.javaVersions.all, scala = c.scalaVersions.all }
               }
             , env.SCALA_VERSION = "\${{ matrix.scala }}"
             }
diff --git a/dhall/common.dhall b/dhall/common.dhall
index 64988f1e..a423ef30 100644
--- a/dhall/common.dhall
+++ b/dhall/common.dhall
@@ -2,25 +2,25 @@ let SimpleObject = List { mapKey : Text, mapValue : Text }
 
 let Uses =
       { Type =
-          { name : Optional Text, uses : Text, with : Optional SimpleObject }
-      , default = { name = None Text, with = None SimpleObject }
+          { name : Optional Text, uses : Text, `with` : Optional SimpleObject }
+      , default = { name = None Text, `with` = None SimpleObject }
       }
 
 let Run =
       { Type =
           { name : Text
           , run : Text
-          , if : Optional Text
+          , `if` : Optional Text
           , env : Optional SimpleObject
           }
-      , default = { if = None Text, env = None SimpleObject }
+      , default = { `if` = None Text, env = None SimpleObject }
       }
 
 let BuildStep = < Uses : Uses.Type | Run : Run.Type >
 
 let baseJob = \(steps : List BuildStep) -> { runs-on = "ubuntu-latest", steps }
 
-let javaVersions = let dv = "11" in { default = dv, all = [ dv, "14" ] }
+let javaVersions = ./javaVersions.dhall
 
 let scalaVersions = ./scalaVersions.dhall
 
@@ -39,7 +39,7 @@ let steps =
               ->  BuildStep.Uses
                     Uses::{
                     , uses = "actions/setup-java@v1"
-                    , with = Some (toMap { java-version = version })
+                    , `with` = Some (toMap { java-version = version })
                     }
           , cache =
               let cacheConfig =
@@ -48,7 +48,7 @@ let steps =
                           Uses::{
                           , name = Some config.name
                           , uses = "actions/cache@v1"
-                          , with = Some
+                          , `with` = Some
                               ( toMap
                                   { path = config.path
                                   , key =
diff --git a/dhall/dhall.dhall b/dhall/dhall.dhall
index 3a684ca3..55661228 100644
--- a/dhall/dhall.dhall
+++ b/dhall/dhall.dhall
@@ -1,44 +1,14 @@
 let c = ./common.dhall
 
-let versions = { dhall = "1.31.1", dhallToYaml = "1.6.3" }
-
-let dhallDownload =
-          \(file : Text)
-      ->  let baseUrl =
-                "https://github.com/dhall-lang/dhall-haskell/releases/download"
-
-          in  "curl -L ${baseUrl}/${versions.dhall}/${file}-x86_64-linux.tar.bz2 | tar xj"
-
 let steps =
       [ c.steps.checkout
-      , c.BuildStep.Run
-          c.Run::{
-          , name = "Setup Dhall"
-          , run =
-              ''
-              cd $(mktemp -d)
-              ${dhallDownload "dhall-${versions.dhall}"}
-              ${dhallDownload "dhall-json-${versions.dhallToYaml}"}
-              mkdir -p $HOME/bin
-              mv bin/* $HOME/bin/
-              echo "::add-path::$HOME/bin"
-              ''
-          }
-      , c.BuildStep.Run
-          c.Run::{
-          , name = "Check Dhall formatting"
-          , run =
-              ''
-              [[ $(find -name '*.dhall' -exec sh -c 'dhall --ascii format --check < {}' \; |& wc -c) -eq 0 ]]
-              ''
-          }
+      , c.steps.java c.javaVersions.default
       , c.BuildStep.Run
           c.Run::{
           , name = "Check generated YAML files"
           , run =
               ''
-              cd dhall
-              ./generateYaml.sh
+              sbt convertDhall
               [[ $(git status --porcelain | wc -l) -eq 0 ]]
               ''
           }
diff --git a/dhall/dhallFormat.sh b/dhall/dhallFormat.sh
deleted file mode 100755
index e9251bc6..00000000
--- a/dhall/dhallFormat.sh
+++ /dev/null
@@ -1,2 +0,0 @@
-cd $(dirname "$0")
-find -name '*.dhall' -exec dhall --ascii format --inplace {} \;
diff --git a/dhall/generateYaml.sh b/dhall/generateYaml.sh
deleted file mode 100755
index 270cb778..00000000
--- a/dhall/generateYaml.sh
+++ /dev/null
@@ -1,9 +0,0 @@
-cd $(dirname "$0")
-
-for f in ci release dhall; do
-    dhall-to-yaml --omit-empty --file $f.dhall --output ../.github/workflows/$f.yml
-done
-
-dhall-to-yaml --omit-empty --file mergify.dhall --output ../.mergify.yml
-
-dhall-to-json --file scalaVersions.dhall --output ../scalaVersions.json
diff --git a/dhall/javaVersions.dhall b/dhall/javaVersions.dhall
new file mode 100644
index 00000000..eebc3d96
--- /dev/null
+++ b/dhall/javaVersions.dhall
@@ -0,0 +1 @@
+let default = "11" in { default, all = [ default, "14" ] }
diff --git a/dhall/mergify.dhall b/dhall/mergify.dhall
index a6dd2067..04d17f20 100644
--- a/dhall/mergify.dhall
+++ b/dhall/mergify.dhall
@@ -15,14 +15,14 @@ let ciJobNameRules =
                 )
                 c.javaVersions.all
         )
-        c.scalaVersions
+        c.scalaVersions.all
 
 in  { pull_request_rules =
       [ { name = "automatically merge scala-steward's PRs"
         , conditions =
               [ "author=scala-steward", "body~=labels:.*semver-patch.*" ]
             # ciJobNameRules
-        , actions.merge.method = "merge"
+        , actions.`merge`.method = "merge"
         }
       ]
     }
diff --git a/dhall/scalaVersions.dhall b/dhall/scalaVersions.dhall
index 6a55d58c..04fa9b6b 100644
--- a/dhall/scalaVersions.dhall
+++ b/dhall/scalaVersions.dhall
@@ -1 +1 @@
-[ "2.12.11", "2.13.1" ]
+let default = "2.12.11" in { default, all = [ default, "2.13.1" ] }
diff --git a/project/Dhall.scala b/project/Dhall.scala
new file mode 100644
index 00000000..9bcc8d08
--- /dev/null
+++ b/project/Dhall.scala
@@ -0,0 +1,58 @@
+import cats.effect._
+import java.nio.file.{Files, Paths}
+import org.dhallj.core.Expr
+import org.dhallj.core.converters.JsonConverter
+import org.dhallj.imports.syntax._
+import org.dhallj.parser.DhallParser
+import org.dhallj.yaml.YamlConverter
+import org.http4s.client.Client
+import org.http4s.client.jdkhttpclient.JdkHttpClient
+import sbt.{IO => _, _}
+import scala.concurrent.ExecutionContext
+import upickle.default.{ReadWriter, macroRW}
+
+object Dhall {
+
+  lazy val convertDhall = taskKey[Unit]("Generate YAML/JSON from Dhall.")
+
+  private lazy val http = {
+    implicit val cs: ContextShift[IO] = IO.contextShift(ExecutionContext.global)
+    JdkHttpClient.simple[IO].unsafeRunSync()
+  }
+
+  private def loadDhall(expr: String): Expr = {
+    implicit val c: Client[IO] = http
+    DhallParser
+      .parse(expr)
+      .normalize()
+      .resolveImports[IO]
+      .unsafeRunSync()
+      .normalize()
+  }
+
+  val convertDhallTask = convertDhall := {
+    val baseDir = (Keys.baseDirectory in LocalRootProject).value.absolutePath
+    def convertYaml(from: String, to: String): Unit = {
+      val dhall = loadDhall(s"$baseDir/dhall/$from.dhall")
+      val yaml = YamlConverter.toYamlString(dhall)
+      Files.writeString(Paths.get(s"$baseDir/$to"), yaml)
+    }
+    List("ci", "release", "dhall").foreach { file =>
+      convertYaml(file, s".github/workflows/$file.yml")
+    }
+    convertYaml("mergify", s".mergify.yml")
+  }
+
+  case class ScalaVersions(default: String, all: List[String])
+  object ScalaVersions { implicit val rw: ReadWriter[ScalaVersions] = macroRW }
+
+  val scalaVersions = settingKey[ScalaVersions]("Read the Scala versions via Dhall")
+
+  val scalaVersionsImpl = scalaVersions := {
+    val baseDir = (Keys.baseDirectory in LocalRootProject).value.absolutePath
+    val dhall = loadDhall(s"$baseDir/dhall/scalaVersions.dhall")
+    val json = JsonConverter.toCompactString(dhall)
+    upickle.default.read[ScalaVersions](json)
+  }
+
+}
diff --git a/project/build.sbt b/project/build.sbt
index 9580ea08..57e2ae83 100644
--- a/project/build.sbt
+++ b/project/build.sbt
@@ -1,3 +1,14 @@
+val dhalljV = "0.2.0"
+val http4sJdkHttpClientV = "0.3.0"
+val upickleV = "1.1.0"
+
+// format: off
 libraryDependencies ++= Seq(
-  "com.lihaoyi" %% "upickle" % "1.1.0"
+  "org.dhallj"  %  "dhall-core"             % dhalljV,
+  "org.dhallj"  %  "dhall-parser"           % dhalljV,
+  "org.dhallj"  %  "dhall-yaml"             % dhalljV,
+  "org.dhallj"  %% "dhall-imports"          % dhalljV,
+  "org.http4s"  %% "http4s-jdk-http-client" % http4sJdkHttpClientV,
+  "com.lihaoyi" %% "upickle"                % upickleV
 )
+// format: on
diff --git a/scalaVersions.json b/scalaVersions.json
deleted file mode 100644
index 462f94cf..00000000
--- a/scalaVersions.json
+++ /dev/null
@@ -1,4 +0,0 @@
-[
-  "2.12.11",
-  "2.13.1"
-]