Lambda Expressions

A lambda expression is a procedure without a name that you can use as an alternative to a named event handler. You can write a lambda expression on one line or as a block of statements. Lambda expressions can use the semantics of one of the statements Function or Sub. A lambda expression with the semantics of Sub has access to the local scope.

You make a lambda expression with one of the keywords Function or Sub, almost the same as the statements that use these keywords. The difference is that lambda expressions are a part of a statement.

In the example that follows, lambda expressions add to a value. The example shows the one-line and block constructs for a function.

Var add1 = Function(x) x + 1
Var add2 = Function(x)
        Return x + 2
    End Function

Print add1(1)
Print add2(2)

2
4

Lambda expression syntax

The syntax of a lambda expression is almost the same as a typical procedure. The differences are as follows:

• A lambda expression does not have a name.
• Lambda expressions cannot have modifiers, for example, @Abstract or @MustUse.
• The body of the one-line construct must be an expression that returns a value, not a statement.
• The one-line construct is not completed with one of the clauses End, End Function, or End Sub.
• Optional parameters are not permitted.
• Generic parameters are not permitted.

Context

TODO

See also

• Events
• Function Statement
• sub Statement