2iota
From Esolang
2iota is an esoteric programming language devised by Chris Pressey in 2004. The successor to beta-Juliet and Portia, it is fairly minimal, aiming to be an event-oriented Turing tarpit.
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[edit] Etymology
The name 2iota, like the names of beta-Juliet and Portia, comes from a "alphabetical" pun on the name of a make of car. It is pronounced /too-eye-OH-tah/.
There is no relationship between 2iota and Iota, nor between 2iota and Biota.
[edit] Language description
A 2iota program consists of a set of events. Each event is named by a string of one or more symbols and optionally a pattern. Each event also names what events it causes in a chain reaction.
A program can also define one or more finite alphabets. If the symbols in the name of an event are members of an alphabet, they can be 'incremented' and 'decremented'.
[edit] Example programs
The following program implements a 1Hz "clock":
event Oscillator goes High, causes Oscillator goes Low after 0.5 s; event Oscillator goes Low, causes Oscillator goes High after 0.5 s.
[edit] Computational class
Unlike beta-Juliet (which lacked patterns) and Portia (which allowed only a finite expansion of patterns), 2iota allows a technique something like Gödel numbering to construct names of events; in this manner concepts such as an (unboundedly) "next" event can be named, as illustrated in the following example.
alphabet DominoNumber,
One, Two, Three, Four, Five, Six, Seven;
event Begin,
causes Domino One Falls;
event Domino (N = DominoNumber+) Falls,
causes Domino (succ N) Falls.
Since this implements a simple (runaway!) unbounded counter, the author suspects 2iota to be Turing-complete through isomorphism with a Minsky machine. This has not yet been formally proven, however.
