Issue 214 and 205

core/jvm/src/main/scala/zio/sql/expr.scala

@@ -162,6 +162,11 @@ trait ExprModule extends NewtypesModule with FeaturesModule with OpsModule {
       def typeTag: TypeTag[Z] = implicitly[TypeTag[Z]]
     }
 
+    sealed case class ParenlessFunctionCall0[Z: TypeTag](function: FunctionName)
+        extends InvariantExpr[Features.Function0, Any, Z] {
+      def typeTag: TypeTag[Z] = implicitly[TypeTag[Z]]
+    }
+
     sealed case class FunctionCall0[Z: TypeTag](function: FunctionDef[Any, Z])
         extends InvariantExpr[Features.Function0, Any, Z] {
       def typeTag: TypeTag[Z] = implicitly[TypeTag[Z]]
@@ -219,7 +224,7 @@ trait ExprModule extends NewtypesModule with FeaturesModule with OpsModule {
 
   sealed case class FunctionDef[-A, +B](name: FunctionName) { self =>
 
-    def apply[B1 >: B]()(implicit typeTag: TypeTag[B1]): Expr[Features.Function0, Any, B1] =
+    def apply[B1 >: B]()(implicit ev: Any <:< A, typeTag: TypeTag[B1]): Expr[Features.Function0, Any, B1] =
       Expr.FunctionCall0(self.asInstanceOf[FunctionDef[Any, B1]])
 
     def apply[F, Source, B1 >: B](param1: Expr[F, Source, A])(implicit typeTag: TypeTag[B1]): Expr[F, Source, B1] =

postgres/src/main/scala/zio/sql/postgresql/PostgresModule.scala

@@ -1,23 +1,25 @@
 package zio.sql.postgresql
 
-import zio.sql.{ Jdbc, Renderer }
+import java.time._
 
-import java.time.{ Instant, LocalDate, LocalTime, ZonedDateTime }
+import zio.sql.{ Jdbc, Renderer }
 
 /**
  */
 trait PostgresModule extends Jdbc { self =>
 
   object PostgresFunctionDef {
+    val TimeOfDay                   = FunctionDef[Any, String](FunctionName("timeofday"))
+    val CurrentTime                 = Expr.ParenlessFunctionCall0[OffsetTime](FunctionName("current_time"))
     val CharLength                  = FunctionDef[String, Int](FunctionName("character_length"))
-    val Localtime                   = FunctionDef[Any, LocalTime](FunctionName("localtime"))
+    val Localtime                   = Expr.ParenlessFunctionCall0[LocalTime](FunctionName("localtime"))
     val LocaltimeWithPrecision      = FunctionDef[Int, LocalTime](FunctionName("localtime"))
-    val Localtimestamp              = FunctionDef[Any, Instant](FunctionName("localtimestamp"))
+    val Localtimestamp              = Expr.ParenlessFunctionCall0[Instant](FunctionName("localtimestamp"))
     val LocaltimestampWithPrecision = FunctionDef[Int, Instant](FunctionName("localtimestamp"))
     val Md5                         = FunctionDef[String, String](FunctionName("md5"))
     val ParseIdent                  = FunctionDef[String, String](FunctionName("parse_ident"))
     val Chr                         = FunctionDef[Int, String](FunctionName("chr"))
-    val CurrentDate                 = FunctionDef[Any, LocalDate](FunctionName("current_date"))
+    val CurrentDate                 = Expr.ParenlessFunctionCall0[LocalDate](FunctionName("current_date"))
     val Initcap                     = FunctionDef[String, String](FunctionName("initcap"))
     val Repeat                      = FunctionDef[(String, Int), String](FunctionName("repeat"))
     val Reverse                     = FunctionDef[String, String](FunctionName("reverse"))
@@ -160,7 +162,12 @@ trait PostgresModule extends Jdbc { self =>
         render(aggregation.name.name, "(")
         renderExpr(p)
         render(")")
-      case Expr.FunctionCall0(fn)                 => render(fn.name.name) //todo parens or no parens?
+      case Expr.ParenlessFunctionCall0(fn)        =>
+        val _ = render(fn.name)
+      case Expr.FunctionCall0(fn)                 =>
+        render(fn.name.name)
+        render("(")
+        val _ = render(")")
       case Expr.FunctionCall1(p, fn)              =>
         render(fn.name.name, "(")
         renderExpr(p)

postgres/src/test/scala/zio/sql/postgresql/FunctionDefSpec.scala

@@ -212,8 +212,23 @@ object FunctionDefSpec extends PostgresRunnableSpec with ShopSchema {
 
       assertion.mapErrorCause(cause => Cause.stackless(cause.untraced))
     },
+    testM("timeofday") {
+      val query = select(TimeOfDay()) from customers
+
+      val testResult = execute(query).to[String, String](identity)
+
+      val assertion =
+        for {
+          r <- testResult.runCollect
+        } yield assert(r.head)(
+          matchesRegex(
+            "[A-Za-z]{3}\\s[A-Za-z]{3}\\s[0-9]{2}\\s(2[0-3]|[01][0-9]):[0-5][0-9]:[0-5][0-9].[0-9]{6}\\s[0-9]{4}\\s[A-Za-z]{3}"
+          )
+        )
+      assertion.mapErrorCause(cause => Cause.stackless(cause.untraced))
+    },
     testM("localtime") {
-      val query = select(Localtime()) from customers
+      val query = select(Localtime) from customers
 
       val testResult = execute(query).to[LocalTime, LocalTime](identity)
 
@@ -236,7 +251,7 @@ object FunctionDefSpec extends PostgresRunnableSpec with ShopSchema {
       assertion.mapErrorCause(cause => Cause.stackless(cause.untraced))
     },
     testM("localtimestamp") {
-      val query = select(Localtimestamp()) from customers
+      val query = select(Localtimestamp) from customers
 
       val testResult = execute(query).to[Instant, Instant](identity)
 
@@ -270,6 +285,22 @@ object FunctionDefSpec extends PostgresRunnableSpec with ShopSchema {
 
       assertion.mapErrorCause(cause => Cause.stackless(cause.untraced))
     },
+    testM("current_time") {
+      val query = select(CurrentTime) from customers
+
+      val testResult = execute(query).to[OffsetTime, OffsetTime](identity)
+
+      val assertion =
+        for {
+          r <- testResult.runCollect
+        } yield assert(r.head.toString)(
+          matchesRegex(
+            "(2[0-3]|[01][0-9]):[0-5][0-9]:[0-5][0-9]Z"
+          )
+        )
+
+      assertion.mapErrorCause(cause => Cause.stackless(cause.untraced))
+    },
     testM("md5") {
       val query = select(Md5("hello, world!")) from customers
 
@@ -343,7 +374,7 @@ object FunctionDefSpec extends PostgresRunnableSpec with ShopSchema {
       assertion.mapErrorCause(cause => Cause.stackless(cause.untraced))
     },
     testM("current_date") {
-      val query = select(CurrentDate()) from customers
+      val query = select(CurrentDate) from customers
 
       val expected = LocalDate.now()
 

sqlserver/src/main/scala/zio/sql/sqlserver/SqlServerModule.scala

@@ -38,8 +38,12 @@ trait SqlServerModule extends Jdbc { self =>
         builder.append("(")
         buildExpr(param)
         val _ = builder.append(")")
+      case Expr.ParenlessFunctionCall0(function)                        =>
+        val _ = builder.append(function.name)
       case Expr.FunctionCall0(function)                                 =>
-        val _ = builder.append(function.name.name)
+        builder.append(function.name.name)
+        builder.append("(")
+        val _ = builder.append(")")
       case Expr.FunctionCall1(param, function)                          =>
         builder.append(function.name.name)
         builder.append("(")