File: Add with-input-from-file and with-output-to-file

This also fixes a few logic and error messaging bugs in other related
methods.

Colibri.Core/Macros/PortMacros.cs

@@ -206,7 +206,7 @@ public static object ReadU8(ColibriRuntime runtime, Scope scope, object?[] args)
 
     public static object ReadBytevector(ColibriRuntime runtime, Scope scope, object?[] args)
     {
-        if (args.Length > 1)
+        if (args.Length is 0 or > 2)
         {
             throw new ArgumentException("read-bytevector requires one or two arguments");
         }
@@ -320,7 +320,7 @@ public static object Read(ColibriRuntime runtime, Scope scope, object?[] args)
     {
         if (args.Length > 1)
         {
-            throw new ArgumentException("read-line requires zero or one arguments");
+            throw new ArgumentException("read requires zero or one arguments");
         }
 
         object? port = GetInputPort(runtime, scope, args.Length == 1 ? args[0] : null);
@@ -587,4 +587,38 @@ public static object WriteBytevector(ColibriRuntime runtime, Scope scope, object
 
         return Nil.Value;
     }
+
+    public static object? WithInputFromFile(ColibriRuntime runtime, Scope scope, object?[] args)
+    {
+        if (args.Length != 2 || runtime.Evaluate(scope, args[0]) is not string filename)
+        {
+            throw new ArgumentException("with-input-from-file requires one filename argument and one thunk argument");
+        }
+
+        var thunk = runtime.Evaluate(scope, args[1]);
+
+        using var fileStream = File.OpenRead(filename);
+
+        var childScope = scope.CreateChildScope();
+        childScope.Define("current-input-port", new Parameter(fileStream));
+
+        return runtime.InvokePossibleTailCallExpression(childScope, thunk, Array.Empty<object?>());
+    }
+
+    public static object? WithOutputToFile(ColibriRuntime runtime, Scope scope, object?[] args)
+    {
+        if (args.Length != 2 || runtime.Evaluate(scope, args[0]) is not string filename)
+        {
+            throw new ArgumentException("with-output-to-file requires one filename argument and one thunk argument");
+        }
+
+        var thunk = runtime.Evaluate(scope, args[1]);
+
+        using var fileStream = File.OpenWrite(filename);
+
+        var childScope = scope.CreateChildScope();
+        childScope.Define("current-output-port", new Parameter(fileStream));
+
+        return runtime.InvokePossibleTailCallExpression(childScope, thunk, Array.Empty<object?>());
+    }
 }

Colibri.Core/StandardLibraries.cs

@@ -379,7 +379,8 @@ static StandardLibraries()
         ["open-binary-output-file"] = PortExpressions.OpenBinaryOutputFile,
         ["open-input-file"] = PortExpressions.OpenInputFile,
         ["open-output-file"] = PortExpressions.OpenOutputFile,
-        // TODO: write-input-from-file, write-output-to-file
+        ["with-input-from-file"] = (MacroExpression)PortMacros.WithInputFromFile,
+        ["with-output-to-file"] = (MacroExpression)PortMacros.WithOutputToFile,
     }, additionalExports: new List<string>
     {
         "call-with-input-file",

Colibri.Tests/PortTests.cs

@@ -88,4 +88,29 @@ public void CallWithPortTests(string input, object expected)
     {
         TestHelper.DefaultTest(input, expected);
     }
+
+    [Fact]
+    public void WithInputOutputTest()
+    {
+        const string program = @"
+(define msg ""Hello world!"")
+(with-output-to-file ""WithInputOutputTest.txt""
+  (lambda ()
+    (write-bytevector (string->utf8 msg) (current-output-port))))
+
+(define result (with-input-from-file ""WithInputOutputTest.txt""
+  (lambda ()
+    (utf8->string (read-bytevector (string-length msg) (current-input-port))))))
+
+(delete-file ""WithInputOutputTest.txt"")
+
+result
+";
+
+        var runtime = new ColibriRuntime();
+
+        var result = runtime.EvaluateProgram(program);
+
+        Assert.Equal("Hello world!", result);
+    }
 }