AsTMa? Concepts: Functions

Function provenience:

encapsulate particular functional behaviour
can be predefined: from the package standard
can be imported via the evaluation context: association via a prefix like in XML
can be user-defined within the query

Structure

name
parameter and result profile: via types
expect parameters with the correct types
return a value with the correct type

Scope

functions are only visible in the scope where they are defined, no namespace pollution
formal parameters are only visible in the scope of the defined function

Limitations

functions are NOT objects: no passing around of function objects
no lazy evaluation defined (yet)
no closures (incompletely evaluated functions) defined (yet)