public override IUnboundExpr Transform(LetExpr expr)
{
// a let expression desugars like this:
//
// let a b <- Foo then Bar else Bang
//
// becomes...
//
// def let__ <- Foo
// if Some? let__ then
// def a b <- 0 SomeValue let__
// Bar
// else Bang
var c = new CodeBuilder(mNameGenerator, expr.Position);
var option = c.TempName();
return(c.Block(
c.Def(option, expr.Condition),
c.If(c.Call("Some?", option),
c.Block(
c.Def(expr.Names, c.Call("SomeValue", option)),
expr.ThenBody),
expr.ElseBody)));
}
public virtual IUnboundExpr Transform(LetExpr expr)
{
return(expr);
}
IBoundExpr IUnboundExprVisitor<IBoundExpr>.Visit(LetExpr expr)
{
throw new NotSupportedException("Let expressions should be desugared to more primitive expressions before binding.");
}
IUnboundExpr IUnboundExprVisitor <IUnboundExpr> .Visit(LetExpr expr)
{
throw new NotImplementedException();
}