add markdown-table module

build.sbt

@@ -6,7 +6,7 @@ default(
 )
 
 lazy val bytes = crossProject.settings(
-  v"1.2.1",
+  v"1.2.0",
   dep(
     case_app,
     cats
@@ -17,7 +17,7 @@ lazy val `bytes.jvm` = bytes.jvm
 lazy val `bytes-x`   = parent(`bytes.js`, `bytes.jvm`)
 
 lazy val channel = project.settings(
-  v"1.5.0",
+  v"1.5.1",
   dep(
     log4j tests,
     math.utils % "2.2.0",
@@ -34,9 +34,9 @@ lazy val io = crossProject.settings(
   dep(
     case_app,
     cats,
-    iterators       % "2.1.0",
+    iterators       % "2.2.0",
     shapeless_utils % "1.3.0",
-    types           % "1.1.0"
+    types           % "1.2.0"
   ),
   consoleImport(
     "hammerlab.lines._",
@@ -52,9 +52,24 @@ lazy val `io.jvm` = io.jvm.settings(
 )
 lazy val `io-x` = parent(`io.js`, `io.jvm`)
 
+lazy val markdown = crossProject.settings(
+  v"0.1.0",
+  dep(
+    hammerlab.math.format % "1.0.0",
+    shapeless
+  )
+)
+.dependsOn(
+  io
+)
+lazy val `markdown.js`  = markdown.js
+lazy val `markdown.jvm` = markdown.jvm
+lazy val `markdown-x`   = parent(`markdown.js`, `markdown.jvm`)
+
 lazy val `io-utils` =
   root(
     channel,
     `bytes-x`,
-    `io-x`
+    `io-x`,
+    `markdown-x`
   )

markdown/shared/src/main/scala/hammerlab/markdown.scala

@@ -0,0 +1,10 @@
+package hammerlab
+
+import org.hammerlab.markdown.table.HasTable
+
+trait markdown {
+  trait table extends HasTable
+  object table extends table
+}
+
+object markdown extends markdown with HasTable

markdown/shared/src/main/scala/org/hammerlab/markdown/table/HasTable.scala

@@ -0,0 +1,94 @@
+package org.hammerlab.markdown.table
+
+import hammerlab.lines._
+import org.hammerlab.markdown.table.Header.Entry
+
+trait HasTable {
+
+  object sep {
+    val   left = "---"
+    val center = ":-:"
+    val  right = "--:"
+  }
+
+  case class InvalidFieldOverrides(overrides: Iterable[String])
+    extends IllegalArgumentException(
+      s"Invalid field overrides: ${overrides.mkString(",")}"
+    )
+
+  def apply[T](
+    ts: Seq[T],
+    overrides: (Symbol, String)*
+  )(
+    implicit
+     toRow:  ToRow[T],
+    header: Header[T]
+  ):
+    Lines = {
+
+    val overrideMap =
+      overrides
+        .map {
+          case (n, display) ⇒
+            n.name → display
+        }
+        .toMap
+
+    val headers = header()
+    val headerMap =
+      headers
+        .map {
+          case Entry(name, display) ⇒
+            name → display
+        }
+        .toMap
+
+    overrideMap
+      .keys
+      .filter(!headerMap.contains(_)) match {
+        case missings
+          if missings.nonEmpty ⇒
+          throw InvalidFieldOverrides(missings)
+        case _ ⇒
+      }
+
+    val hdr =
+      headers
+        .map {
+          case Entry(name, display) ⇒
+            overrideMap.getOrElse(name, display)
+        }
+    val seps = Seq.fill(hdr.size)(sep.left)
+    val rows = ts.map(toRow(_)).toList
+    val lines =
+       hdr ::
+      seps ::
+      rows
+    Lines(
+      lines
+        .map(
+          _.mkString(
+             "| ",
+            " | ",
+            " |"
+          ):
+          Lines
+        )
+    )
+  }
+
+  implicit class MarkdownTableOps[T](ts: Seq[T]) {
+    def mdTable(
+      overrides: (Symbol, String)*
+    )(
+      implicit
+      toRow:  ToRow[T],
+      header: Header[T]
+    ):
+    Lines =
+      apply(
+        ts,
+        overrides: _*
+      )
+  }
+}

markdown/shared/src/main/scala/org/hammerlab/markdown/table/Header.scala

@@ -0,0 +1,69 @@
+package org.hammerlab.markdown.table
+
+import hammerlab.iterator._
+import hammerlab.lines._
+import hammerlab.show._
+import org.hammerlab.markdown.table.Header.Entry
+
+trait Header[T] {
+  def apply(): Seq[Entry]
+}
+object Header {
+  case class Entry(name: String, display: String)
+  object Entry {
+    implicit val show: Show[Entry] = Show { _.display }
+  }
+
+  def apply[T](fn: () ⇒ Seq[Entry]): Header[T] =
+    new Header[T] {
+      def apply(): Seq[Entry] = fn()
+    }
+
+  val regex = "[A-Z]?[a-z]+".r
+  def display(name: String): String = {
+    regex
+      .findAllMatchIn(name)
+      .sliding2Opt
+      .flatMap {
+        case (cur, nextOpt) ⇒
+          val next = nextOpt.map(_.start).getOrElse(name.length)
+          val start = cur.start
+          val `match` = cur.matched
+          val first = `match`(0).toUpper + `match`.substring(1)
+          val end = start + first.length
+          if (end != next)
+            Seq(
+              first,
+              name.substring(end, next)
+            )
+          else
+            Seq(
+              first
+            )
+
+      }
+      .mkString(" ")
+  }
+
+  import shapeless._
+  import shapeless.ops.hlist.ToTraversable
+  import shapeless.ops.record._
+
+  implicit def default[T, L <: HList, Out <: HList](
+    implicit
+    g: LabelledGeneric.Aux[T, L],
+    keys: Keys.Aux[L, Out],
+    t: ToTraversable.Aux[Out, List, Symbol]
+  ):
+    Header[T] =
+    Header {
+      () ⇒
+        keys
+          .apply
+          .toList
+          .map(_.name)
+          .map(n ⇒ Entry(n, display(n)))
+    }
+}
+
+

markdown/shared/src/main/scala/org/hammerlab/markdown/table/ToRow.scala

@@ -0,0 +1,52 @@
+package org.hammerlab.markdown.table
+
+import hammerlab.show._
+import shapeless._
+
+trait ToRow[T] {
+  def apply(t: T): Seq[String]
+}
+
+trait LowPriToRow {
+  implicit def fromShow[T](implicit show: Show[T]): ToRow[T] =
+    ToRow {
+      t ⇒ Seq(t.show)
+    }
+}
+
+object ToRow
+  extends LowPriToRow {
+
+  def apply[T](fn: T ⇒ Seq[String]): ToRow[T] =
+    new ToRow[T] {
+      def apply(t: T): Seq[String] = fn(t)
+    }
+
+  implicit def caseClass[T, L <: HList](
+    implicit
+    g: Generic.Aux[T, L],
+    r: Lazy[ToRow[L]]
+  ):
+    ToRow[T] =
+    ToRow {
+      t ⇒
+        r.value(g.to(t))
+    }
+
+  implicit def cons[H, T <: HList](
+    implicit
+    rh: Lazy[ToRow[H]],
+    rt: Lazy[ToRow[T]]
+  ):
+    ToRow[H :: T] =
+    ToRow {
+      case h :: t ⇒
+        (
+          rh.value(h) ++
+          rt.value(t)
+        )
+        .toList
+    }
+
+  implicit val hnil: ToRow[HNil] = ToRow { _ ⇒ Nil }
+}

markdown/shared/src/test/scala/org/hammerlab/markdown/table/Test.scala

@@ -0,0 +1,53 @@
+package org.hammerlab.markdown.table
+
+import hammerlab.indent.spaces
+import hammerlab.markdown._
+import hammerlab.show._
+
+class Test
+  extends hammerlab.Suite {
+
+  // Format [[Double]]s to 2 sig-figs
+  import hammerlab.math.sigfigs._
+  implicit val sigfigs: SigFigs = 2
+
+  val users =
+    Seq(
+      User("abc def", 123.4567),
+      User("ghi jkl mno", 2.34567)
+    )
+
+  test("simple") {
+    ===(
+      users
+        .mdTable()
+        .showLines,
+      """|| User Name | Balance |
+         || --- | --- |
+         || abc def | 123 |
+         || ghi jkl mno | 2.3 |"""
+      .stripMargin
+    )
+  }
+
+  test("override fields") {
+    ===(
+      users
+        .mdTable('balance → "Balance ($)")
+        .showLines,
+      """|| User Name | Balance ($) |
+         || --- | --- |
+         || abc def | 123 |
+         || ghi jkl mno | 2.3 |"""
+      .stripMargin
+    )
+  }
+
+  test("invalid override") {
+    intercept[InvalidFieldOverrides] {
+      users.mdTable('balanc → "Balance…")
+    }
+  }
+}
+
+case class User(userName: String, balance: Double)

project/plugins.sbt

@@ -1 +1 @@
-addSbtPlugin("org.hammerlab.sbt" % "base" % "4.5.1")
+addSbtPlugin("org.hammerlab.sbt" % "base" % "4.6.1")