public void EvalOr_ReturnTruthyItem_WhenAtLeastOneItemIsTrue(ClCell items, ClObj expected)
{
var expr = new ClCell(ClSymbol.Or, items);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(expected));
}
public override IContext Reduce(IContext ctx)
{
var funcName = BuiltIn.Head(Cdr);
var lambda = new ClCell(ClSymbol.Lambda, BuiltIn.Tail(Cdr));
return(BuiltIn.ListOf(ClSymbol.Define, funcName, lambda).Reduce(ctx));
}
public void EvalOr_ReturnLastItem_WhenEachItemIsFalse(ClCell items, ClObj expected)
{
var expr = new ClCell(ClSymbol.Or, items);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(expected));
}
public void EvalAnd_ReturnFalsyItem_WhenAtLeastOneItemIsFalse(ClCell items, ClObj expected)
{
var expr = new ClCell(ClSymbol.And, items);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(expected));
}
public void Eval_ReturnUnreducedExpression_WhenItIsQuoted()
{
var cell = new ClCell(new ClInt(1), new ClInt(2));
var expr = BuiltIn.Quote(cell);
var ctx = expr.Reduce(_ctx);
Assert.That(Object.ReferenceEquals(ctx.Value, cell), Is.True);
}
public static ClCell ListOf(params ClObj[] items)
{
ClCell cell = ClCell.Nil;
for (var i = items.Length - 1; i >= 0; i--)
{
cell = new ClCell(items[i], cell);
}
return(cell);
}
public override IContext Reduce(IContext ctx)
{
var tail = BuiltIn.Tail(Cdr);
if (tail == ClCell.Nil || BuiltIn.Cdr(tail) != ClCell.Nil)
{
throw new SyntaxError("Invalid body of the let special form");
}
var beginBody = VariableDefinitionExpressions().Append(BuiltIn.Car(tail)).ListOf();
var begin = new ClCell(ClSymbol.Begin, beginBody);
var lambda = BuiltIn.ListOf(ClSymbol.Lambda, ClCell.Nil, begin);
return(BuiltIn.ListOf(lambda).Reduce(ctx));
}
