Freya: common expression blocks

Common expression blocks allows factoring out repeated subexpressions in a longer expression, giving it a name and giving the compiler a chance to avoid repeated evaluation.

Syntax

Common expression blocks are very similar to using statements:

using identifier := expression , ... do core-expression

The result type of the whole expression is the type of the core-expression. Local variables are created and initialized for each assignmens from the header. After this, the core expression is evaluated and its value is returned. The scope of the created local variables is restricted to the core expression.

Common expression blocks are very useful for inline implementations like this:

method Normalize: Vector =>
    using len := self.Length do
        if len = 0 then self else self / len;

Common expression blocks

Syntax

See also