feat(sample): Add import

Source/Samples/Sample.FuncLanguage/EvaluationVisitor.cs

@@ -21,6 +21,20 @@ public EvaluationVisitor()
         For<NameNode>(Visit);
         For<CallNode>(Visit);
         For<TupleNode>(Visit);
+        For<ImportNode>(Visit);
+    }
+
+    Value Visit(ImportNode node, Scope scope)
+    {
+        var file = new FileInfo($"{node.Path}.f");
+
+        var content = File.ReadAllText(file.FullName);
+        var parsed = Parser.Parse<ExpressionGrammar>(content, file.FullName);
+        var rewritten = parsed.Tree.Accept(new RewriterVisitor());
+
+        rewritten.Accept(new EvaluationVisitor(), scope);
+
+        return UnitValue.Shared;
     }
 
     Value Visit(BinaryOperatorNode binNode, Scope scope)

Source/Samples/Sample.FuncLanguage/ExpressionGrammar.cs

@@ -35,6 +35,7 @@ protected override void InitParselets()
         Register("->", new LambdaParselet());
 
         Register("if", new IfParselet());
+        Register("import", new ImportParselet());
 
         Block(PredefinedSymbols.SOF, PredefinedSymbols.EOF,
             seperator: PredefinedSymbols.Semicolon);

Source/Samples/Sample.FuncLanguage/Nodes/ImportNode.cs

@@ -0,0 +1,5 @@
+using Silverfly.Nodes;
+
+namespace Sample.FuncLanguage.Nodes;
+
+public record ImportNode(string Path) : AstNode;

Source/Samples/Sample.FuncLanguage/Parselets/ImportParselet.cs

@@ -0,0 +1,21 @@
+using Sample.FuncLanguage.Nodes;
+using Silverfly;
+using Silverfly.Nodes;
+using Silverfly.Parselets;
+
+namespace Sample.FuncLanguage.Parselets;
+
+public class ImportParselet : IPrefixParselet
+{
+    public AstNode Parse(Parser parser, Token token)
+    {
+        var arg = parser.ParseExpression();
+
+        if (arg is LiteralNode { Value: string path })
+        {
+            return new ImportNode(path);
+        }
+
+        return new InvalidNode(token);
+    }
+}

Source/Samples/Sample.FuncLanguage/RewriterVisitor.cs

@@ -17,6 +17,8 @@ public RewriterVisitor()
         For<TupleNode>(Rewrite);
     }
 
+    protected override AstNode VisitUnknown(AstNode node) => node;
+
     private AstNode Rewrite(TupleNode node)
     {
         return node with

Source/Samples/Sample.FuncLanguage/Sample.FuncLanguage.csproj

@@ -11,4 +11,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <None Include="std.f" CopyToOutputDirectory="PreserveNewest"/>
+  </ItemGroup>
+
 </Project>

Source/Samples/Sample.FuncLanguage/ToDo.md

@@ -1,2 +1,3 @@
-[-] implement lambda functions as values
-    lambdas with more than one parameter has to be implemented
+[ ] implement module definition
+[-] implement module import from file (read file, parse and evaluate with the current rootscope)
+[ ] implement to scope to import clr classes/functions

Source/Samples/Sample.FuncLanguage/Values/ModuleValue.cs

@@ -8,4 +8,9 @@ public ModuleValue(Scope scope)
     }
 
     public override bool IsTruthy() => true;
+
+    public override string ToString()
+    {
+        return $"Module with {Members.Bindings.Count} bindings";
+    }
 }

Source/Samples/Sample.FuncLanguage/std.f

@@ -0,0 +1 @@
+let add x y = x + y