feat: add debug construct (#4647)

main/src/ca/uwaterloo/flix/Main.scala

@@ -184,7 +184,7 @@ object Main {
       }
     } catch {
       case ex: RuntimeException =>
-        Console.println(ex.getMessage)
+        ex.printStackTrace()
         System.exit(1)
     }
   }

main/src/ca/uwaterloo/flix/api/lsp/Indexer.scala

@@ -430,6 +430,9 @@ object Indexer {
 
     case Expression.ReifyEff(sym, exp1, exp2, exp3, _, _, _, _) =>
       visitExp(exp1) ++ visitExp(exp2) ++ visitExp(exp3) ++ Index.occurrenceOf(sym, exp1.tpe) ++ Index.occurrenceOf(exp0)
+
+    case Expression.Debug(exp, _, _, _, _) =>
+      visitExp(exp)
   }
 
   /**

main/src/ca/uwaterloo/flix/api/lsp/LocationLink.scala

@@ -65,7 +65,7 @@ object LocationLink {
     * Returns a location link to the given symbol `sym`.
     */
   def fromCaseSym(sym: Symbol.CaseSym, loc: SourceLocation)(implicit root: Root): LocationLink = {
-    val enumDecl = root.enums(sym.enum)
+    val enumDecl = root.enums(sym.enumSym)
     val caseDecl = enumDecl.cases(sym)
     val originSelectionRange = Range.from(loc)
     val targetUri = sym.loc.source.name

main/src/ca/uwaterloo/flix/api/lsp/provider/FindReferencesProvider.scala

@@ -139,7 +139,7 @@ object FindReferencesProvider {
   }
 
   private def findCaseReferences(sym: Symbol.CaseSym)(implicit index: Index, root: Root): JObject = {
-    val defSite = Location.from(root.enums(sym.enum).cases(sym).loc)
+    val defSite = Location.from(root.enums(sym.enumSym).cases(sym).loc)
     val useSites = index.usesOf(sym)
     val locs = defSite :: useSites.toList.map(Location.from)
     ("status" -> "success") ~ ("result" -> locs.map(_.toJSON))

main/src/ca/uwaterloo/flix/api/lsp/provider/HighlightProvider.scala

@@ -133,7 +133,7 @@ object HighlightProvider {
   }
 
   private def highlightCase(sym: Symbol.CaseSym)(implicit index: Index, root: Root): JObject = {
-    val write = (root.enums(sym.enum).cases(sym).loc, DocumentHighlightKind.Write)
+    val write = (root.enums(sym.enumSym).cases(sym).loc, DocumentHighlightKind.Write)
     val reads = index.usesOf(sym).toList.map(loc => (loc, DocumentHighlightKind.Read))
     highlight(write :: reads)
   }

main/src/ca/uwaterloo/flix/api/lsp/provider/SemanticTokensProvider.scala

@@ -537,6 +537,9 @@ object SemanticTokensProvider {
       val o = getSemanticTokenType(sym, exp1.tpe)
       val t = SemanticToken(o, Nil, sym.loc)
       Iterator(t) ++ visitExp(exp1) ++ visitExp(exp2) ++ visitExp(exp3)
+
+    case Expression.Debug(exp, _, _, _, _) =>
+      visitExp(exp)
   }
 
   /**

main/src/ca/uwaterloo/flix/language/ast/KindedAst.scala

@@ -218,6 +218,8 @@ object KindedAst {
 
     case class ReifyEff(sym: Symbol.VarSym, exp1: KindedAst.Expression, exp2: KindedAst.Expression, exp3: KindedAst.Expression, loc: SourceLocation) extends KindedAst.Expression
 
+    case class Debug(exp: KindedAst.Expression, loc: SourceLocation) extends KindedAst.Expression
+
   }
 
   sealed trait Pattern {

main/src/ca/uwaterloo/flix/language/ast/NamedAst.scala

@@ -239,6 +239,8 @@ object NamedAst {
 
     case class ReifyEff(sym: Symbol.VarSym, exp1: NamedAst.Expression, exp2: NamedAst.Expression, exp3: NamedAst.Expression, loc: SourceLocation) extends NamedAst.Expression
 
+    case class Debug(exp: NamedAst.Expression, loc: SourceLocation) extends NamedAst.Expression
+
   }
 
   sealed trait Pattern {

main/src/ca/uwaterloo/flix/language/ast/ParsedAst.scala

@@ -31,10 +31,10 @@ object ParsedAst {
     *
     * A collection of imports and declarations.
     *
-    * @param sp1   the position of the first character in the source.
-    * @param usesOrImports  the uses in the abstract syntax tree.
-    * @param decls the declarations in the abstract syntax tree.
-    * @param sp2   the position of the last character in the source.
+    * @param sp1           the position of the first character in the source.
+    * @param usesOrImports the uses in the abstract syntax tree.
+    * @param decls         the declarations in the abstract syntax tree.
+    * @param sp2           the position of the last character in the source.
     */
   case class CompilationUnit(sp1: SourcePosition, usesOrImports: Seq[ParsedAst.UseOrImport], decls: Seq[ParsedAst.Declaration], sp2: SourcePosition)
 
@@ -1214,6 +1214,15 @@ object ParsedAst {
       */
     case class ReifyPurity(sp1: SourcePosition, exp1: ParsedAst.Expression, ident: Name.Ident, exp2: ParsedAst.Expression, exp3: ParsedAst.Expression, sp2: SourcePosition) extends ParsedAst.Expression
 
+    /**
+      * Debug expression.
+      *
+      * @param sp1 the position of the first character in the expression.
+      * @param exp the expression to print.
+      * @param sp2 the position of the last character in the expression.
+      */
+    case class Debug(sp1: SourcePosition, exp: ParsedAst.Expression, sp2: SourcePosition) extends ParsedAst.Expression
+
   }
 
   /**

main/src/ca/uwaterloo/flix/language/ast/ResolvedAst.scala

@@ -220,6 +220,8 @@ object ResolvedAst {
 
     case class ReifyEff(sym: Symbol.VarSym, exp1: ResolvedAst.Expression, exp2: ResolvedAst.Expression, exp3: ResolvedAst.Expression, loc: SourceLocation) extends ResolvedAst.Expression
 
+    case class Debug(exp: ResolvedAst.Expression, loc: SourceLocation) extends ResolvedAst.Expression
+
   }
 
   sealed trait Pattern {

main/src/ca/uwaterloo/flix/language/ast/SourceLocation.scala

@@ -89,10 +89,29 @@ case class SourceLocation(input: Option[ParserInput], source: Source, locationKi
   }
 
   /**
-    * Returns a formatted string representation of `this` source location.
+    * Returns a string representation of `this` source location with the line number.
+    */
+  def formatWithLine: String = s"${source.name}:$beginLine"
+
+  /**
+    * Returns a string representation of `this` source location with the line and column numbers.
     */
   def format: String = s"${source.name}:$beginLine:$beginCol"
 
+  /**
+    * Returns the source text of the source location.
+    */
+  def text: Option[String] = {
+    if (isMultiLine) {
+      None
+    } else {
+      val line = lineAt(beginLine)
+      val b = Math.min(beginCol - 1, line.length)
+      val e = Math.min(endCol - 1, line.length)
+      Some(line.substring(b, e))
+    }
+  }
+
   /**
     * Returns the hashCode of `this` source location.
     */

main/src/ca/uwaterloo/flix/language/ast/Symbol.scala

@@ -131,8 +131,8 @@ object Symbol {
   /**
     * Returns the case symbol for the given name `ident` in the given `enum`.
     */
-  def mkCaseSym(enum: Symbol.EnumSym, ident: Ident): CaseSym = {
-    new CaseSym(enum, ident.name, ident.loc)
+  def mkCaseSym(sym: Symbol.EnumSym, ident: Ident): CaseSym = {
+    new CaseSym(sym, ident.name, ident.loc)
   }
 
   /**
@@ -411,24 +411,24 @@ object Symbol {
   /**
     * Enum Symbol.
     */
-  final class CaseSym(val enum: Symbol.EnumSym, val name: String, val loc: SourceLocation) {
+  final class CaseSym(val enumSym: Symbol.EnumSym, val name: String, val loc: SourceLocation) {
     /**
       * Returns `true` if this symbol is equal to `that` symbol.
       */
     override def equals(obj: scala.Any): Boolean = obj match {
-      case that: CaseSym => this.enum == that.enum && this.name == that.name
+      case that: CaseSym => this.enumSym == that.enumSym && this.name == that.name
       case _ => false
     }
 
     /**
       * Returns the hash code of this symbol.
       */
-    override val hashCode: Int = Objects.hash(enum, name)
+    override val hashCode: Int = Objects.hash(enumSym, name)
 
     /**
       * Human readable representation.
       */
-    override def toString: String = enum.toString + "." + name
+    override def toString: String = enumSym.toString + "." + name
   }
 
   /**

main/src/ca/uwaterloo/flix/language/ast/TypedAst.scala

@@ -372,6 +372,8 @@ object TypedAst {
 
     case class ReifyEff(sym: Symbol.VarSym, exp1: TypedAst.Expression, exp2: TypedAst.Expression, exp3: TypedAst.Expression, tpe: Type, pur: Type, eff: Type, loc: SourceLocation) extends TypedAst.Expression
 
+    case class Debug(exp: TypedAst.Expression, tpe: Type, pur: Type, eff: Type, loc: SourceLocation) extends TypedAst.Expression
+
   }
 
   sealed trait Pattern {

main/src/ca/uwaterloo/flix/language/ast/WeededAst.scala

@@ -66,7 +66,7 @@ object WeededAst {
   sealed trait Import
 
   object Import {
-    
+
     case class Import(name: Name.JavaName, alias: Name.Ident, loc: SourceLocation) extends WeededAst.Import
 
   }
@@ -241,6 +241,8 @@ object WeededAst {
 
     case class ReifyEff(ident: Name.Ident, exp1: WeededAst.Expression, exp2: WeededAst.Expression, exp3: WeededAst.Expression, loc: SourceLocation) extends WeededAst.Expression
 
+    case class Debug(exp: WeededAst.Expression, loc: SourceLocation) extends WeededAst.Expression
+
   }
 
   sealed trait Pattern {

main/src/ca/uwaterloo/flix/language/ast/ops/TypedAstOps.scala

@@ -283,6 +283,9 @@ object TypedAstOps {
       case Expression.ReifyEff(_, exp1, exp2, exp3, _, _, _, _) =>
         visitExp(exp1, env0) ++ visitExp(exp2, env0) ++ visitExp(exp3, env0)
 
+      case Expression.Debug(exp, _, _, _, _) =>
+        visitExp(exp, env0)
+
     }
 
     /**
@@ -450,6 +453,7 @@ object TypedAstOps {
     case Expression.Reify(_, _, _, _, _) => Set.empty
     case Expression.ReifyType(_, _, _, _, _, _) => Set.empty
     case Expression.ReifyEff(_, exp1, exp2, exp3, _, _, _, _) => sigSymsOf(exp1) ++ sigSymsOf(exp2) ++ sigSymsOf(exp3)
+    case Expression.Debug(exp, _, _, _, _) => sigSymsOf(exp)
   }
 
   /**
@@ -735,6 +739,9 @@ object TypedAstOps {
     case Expression.ReifyEff(sym, exp1, exp2, exp3, _, _, _, _) =>
       (freeVars(exp1) ++ freeVars(exp2) ++ freeVars(exp3)) - sym
 
+    case Expression.Debug(exp, _, _, _, _) =>
+      freeVars(exp)
+
   }
 
   /**

main/src/ca/uwaterloo/flix/language/dbg/FormatExpression.scala

@@ -92,6 +92,7 @@ object FormatExpression {
     case TypedAst.Expression.Reify(t, _, _, _, _) => s"Reify($t)"
     case TypedAst.Expression.ReifyType(t, k, _, _, _, _) => s"ReifyType($t, $k)"
     case TypedAst.Expression.ReifyEff(sym, exp1, exp2, exp3, _, _, _, _) => s"ReifyEff($sym, $exp1, $exp2, $exp3)"
+    case TypedAst.Expression.Debug(exp, _, _, _, _) => s"Debug($exp)"
   }
 
 }

main/src/ca/uwaterloo/flix/language/dbg/PrettyPrinter.scala

@@ -456,6 +456,7 @@ object PrettyPrinter {
         case Expression.Force(exp, tpe, loc) => "force " + visitExp(exp)
 
         case Expression.HoleError(sym, tpe, loc) => formatter.red("HoleError")
+
         case Expression.MatchError(tpe, loc) => formatter.red("MatchError")
       }
 

main/src/ca/uwaterloo/flix/language/phase/EarlyTreeShaker.scala

@@ -357,6 +357,9 @@ object EarlyTreeShaker {
     case Expression.Without(exp, _, _, _, _, _) =>
       visitExp(exp)
 
+    case Expression.Debug(exp, _, _, _, _) =>
+      visitExp(exp)
+
     case Expression.FixpointConstraintSet(_, _, _, loc) =>
       throw InternalCompilerException(s"Unexpected expression near: ${loc.format}.")
 

main/src/ca/uwaterloo/flix/language/phase/Inliner.scala

@@ -274,7 +274,7 @@ object Inliner {
 
     case OccurrenceAst.Expression.Is(sym, exp, purity, loc) =>
       val e = visitExp(exp, subst0)
-      val enum0 = root.enums(sym.enum)
+      val enum0 = root.enums(sym.enumSym)
       if (enum0.cases.size == 1 && e.purity == Pure)
           LiftedAst.Expression.True(loc)
       else

main/src/ca/uwaterloo/flix/language/phase/Kinder.scala

@@ -812,6 +812,11 @@ object Kinder {
         case (e1, e2, e3) => KindedAst.Expression.ReifyEff(sym, e1, e2, e3, loc)
       }
 
+    case ResolvedAst.Expression.Debug(exp, loc) =>
+      mapN(visitExp(exp, kenv0, senv, taenv, henv0, root)) {
+        case e => KindedAst.Expression.Debug(e, loc)
+      }
+
   }
 
   /**

main/src/ca/uwaterloo/flix/language/phase/LateTreeShaker.scala

@@ -286,6 +286,7 @@ object LateTreeShaker {
 
     case Expression.MatchError(_, _) =>
       Set.empty
+
   }
 
   /**

main/src/ca/uwaterloo/flix/language/phase/Lowering.scala

@@ -23,7 +23,7 @@ import ca.uwaterloo.flix.language.ast.TypedAst.Expression.NewChannel
 import ca.uwaterloo.flix.language.ast.TypedAst.Predicate.{Body, Head}
 import ca.uwaterloo.flix.language.ast.TypedAst._
 import ca.uwaterloo.flix.language.ast.ops.TypedAstOps
-import ca.uwaterloo.flix.language.ast.{Ast, Kind, Name, Scheme, SourceLocation, SourcePosition, Symbol, Type, TypeConstructor}
+import ca.uwaterloo.flix.language.ast.{Ast, Kind, Name, Scheme, SemanticOperator, SourceLocation, SourcePosition, Symbol, Type, TypeConstructor}
 import ca.uwaterloo.flix.util.Validation.ToSuccess
 import ca.uwaterloo.flix.util.{InternalCompilerException, ParOps, Validation}
 
@@ -56,6 +56,8 @@ object Lowering {
     lazy val Lift4: Symbol.DefnSym = Symbol.mkDefnSym("Boxable.lift4")
     lazy val Lift5: Symbol.DefnSym = Symbol.mkDefnSym("Boxable.lift5")
 
+    lazy val Debug: Symbol.DefnSym = Symbol.mkDefnSym("debug")
+
     /**
       * Returns the definition associated with the given symbol `sym`.
       */
@@ -675,6 +677,12 @@ object Lowering {
       val e3 = visitExp(exp3)
       Expression.ReifyEff(sym, e1, e2, e3, t, pur, eff, loc)
 
+    case Expression.Debug(exp, tpe, pur, eff, loc) =>
+      val line = s"[${loc.formatWithLine}] "
+      val e1 = Expression.Str(line, loc)
+      val e2 = visitExp(exp)
+      val concat = Expression.Binary(SemanticOperator.StringOp.Concat, e1, e2, Type.Str, e2.pur, e2.eff, loc)
+      mkApplyDebug(concat)
   }
 
   /**
@@ -1428,6 +1436,19 @@ object Lowering {
     mkParChannels(tuple, chanSymsWithExps)
   }
 
+  /**
+    * Applies the given expression `exp` to the `debug` function.
+    */
+  private def mkApplyDebug(exp: Expression)(implicit root: Root, flix: Flix): Expression = {
+    //
+    // Note that we mark the call as impure (even though it may have been typed as pure!)
+    //
+    val loc = exp.loc
+    val tpe = Type.mkImpureArrow(exp.tpe, Type.Unit, loc)
+    val innerExp = Expression.Def(Defs.Debug, tpe, loc)
+    Expression.Apply(innerExp, List(exp), Type.Unit, Type.Impure, Type.Empty, loc)
+  }
+
   /**
     * Return a list of quantified variables in the given expression `exp0`.
     *
@@ -1760,6 +1781,10 @@ object Lowering {
       val e3 = substExp(exp3, subst)
       Expression.ReifyEff(sym, e1, e2, e3, tpe, pur, eff, loc)
 
+    case Expression.Debug(exp, tpe, pur, eff, loc) =>
+      val e = substExp(exp, subst)
+      Expression.Debug(e, tpe, pur, eff, loc)
+
     case Expression.FixpointConstraintSet(_, _, _, loc) => throw InternalCompilerException(s"Unexpected expression near ${loc.format}.")
 
   }

main/src/ca/uwaterloo/flix/language/phase/Monomorph.scala

@@ -661,6 +661,10 @@ object Monomorph {
         } else {
           visitExp(exp3, env0)
         }
+
+      case Expression.Debug(exp, tpe, pur, eff, loc) =>
+        val e = visitExp(exp, env0)
+        Expression.Debug(e, subst0(tpe), pur, eff, loc)
     }
 
     /**