Lava (programming language)

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Lava is an experimental, visual, object-oriented, interpreter-based programming language with an associated programming environment (LavaPE = Lava Programming Environment), which gets along without a text editor, but is totally based on structure editors. Only comments, constants and new identifiers must be entered as text.

Declarations are represented in LavaPE as tree structures whose sub-trees may be collapsed or expanded. The properties of the declared Lava entities can be edited through pop-up dialogs.

Although executable code has a traditional text representation in LavaPE, it can be edited only as complete syntactic units, rather than character by character. If you insert a new syntactic construct, it will typically contain "placeholders" (syntactic variables) which can then be replaced by concrete constructs; the latter may in turn contain syntactic variables, etc. LavaPE provides a tool button for every type of syntactic construct. A button is enabled only if it is syntactically correct to insert the associated construct at the selected place.

Further characteristic properties of Lava and LavaPE include:

It provides strict syntactic separation of interface (= public part) and implementation (= private part) of a Lava class.
It distinguishes variable "state objects" from constant "value objects". The latter cannot be modified any longer after creation/initialization.
It supports "virtual types": type parameters of classes and packages (= families of related classes). As a consequence, undermining of strong type checks by "type casts" is no longer required.
It uses recursion and logical quantifiers instead of traditional loop constructs.
It uses single-assignment: a value can be assigned to a variable only once within the same branch of a function.
It supports refactoring extensively via the LavaPE structure editors.
It distinguishes between constituents (= sub-objects) and object acquaintances (= pointers to independent objects). Copying and deletion of complex objects is largely facilitated in this way.

Lava is open source software using the GPL license. It runs on Microsoft Windows and Linux platforms currently. Enhancements of the LavaPE functionality and further ports are planned.