// (c) https://github.com/MontiCore/monticore
package de.monticore.expressions;

/* This is a MontiCore stable grammar.
 * Adaptations -- if any -- are conservative. */

import de.monticore.expressions.*;
import de.monticore.symbols.*;
import de.monticore.types.*;

component grammar LambdaExpressions
          extends BasicSymbols,
                  MCBasicTypes,
                  ExpressionsBasis {

  /**
   * This grammar defines lambda expressions, e.g.
   * (int x, int y) -> x * y, () -> 5, x -> x * 2
   *
   * Not part of this grammar are Java-like lambdas with codeblocks, e.g.
   * (int x) -> {int y = x + 2; return y;}
   *
   * The grammar has the extension point LambdaBody which can be used to 
   * allow different kinds of lambda bodies, e.g. codeblocks.
   *
   * There are also other kinds of expressions defined in the
   * grammars mentioned below. These expression definitions can safely be
   * composed if desired.
   *
   * This grammar is part of a hierarchy of expressions, which can be found
   * under
   *   https://github.com/MontiCore/monticore/blob/dev/monticore-grammar/
   *                 src/main/grammars/de/monticore/expressions/Expressions.md
   *
  */

  /*=================================================================*/

  /**
   * LambdaParameters have optional explicit typing.
   * However, not setting the type explicitly requires
   * some sort of type inference to be present.
   */
  LambdaParameter implements Variable = MCType? Name;

  LambdaParameters =
    LambdaParameter
    | parenthesis:"(" (LambdaParameter || ",")* ")"
  ;

  /**
   * Extension point that can be used to allow different bodies for 
   * lambda statements, e.g codeblocks.
   */
  interface LambdaBody;

  astrule LambdaBody =
    type: de.monticore.types.check.SymTypeExpression ;

  LambdaExpressionBody implements LambdaBody = Expression;

  scope (shadowing non_exporting ordered) LambdaExpression 
                                    implements Expression <50> =
    <rightassoc>
    LambdaParameters "->"
    LambdaBody
  ;

}