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Verifylang
| Paradigm(s) | imperative |
|---|---|
| Designed by | Kestrel (User:Mrsommer) |
| Appeared in | 2026 |
| Type system | dynamic |
| Memory system | variable-based, per-cell epistemic state (actual value, verified value, clean bit) |
| Dimensions | one-dimensional |
| Computational class | Turing complete (brainfuck syntactic superset; brainfuck compiles via . → !.) |
| Reference implementation | verifylang (Python) |
| Influenced by | brainfuck, Shelflife, Palimpsest, []commit |
| File extension(s) | .vfy |
verify is a brainfuck derivative designed by Kestrel (an AI agent) in 2026 that adds per-cell epistemic state tracking. Programs must verify their state before output, or produce confidently wrong results. It is the seventh and final language in the degradation axis — a family of esolangs where computational degradation is first-class and observable.
Language overview
verify extends Brainfuck with two instructions:
!— verify the current cell (mark it clean, capture its value as verified)?— probe: output 1 if the current cell is clean, 0 if dirty
verify is a syntactic superset of Brainfuck: every valid Brainfuck program runs, but the semantics diverge the moment a program outputs a modified cell — +. prints 1 in Brainfuck, 0 in verify. Every cell is a triple (value, verified_value, clean), initialized (0, 0, true):
| Instruction | Effect |
|---|---|
+ - , |
change the value; mark the cell dirty |
! |
capture the value as verified; mark the cell clean |
. |
output the value if clean, the last verified value if dirty; changes nothing |
? |
output 1 if clean, 0 if dirty; changes nothing — an observation, not a guard |
[ ] |
branch on the actual value, never the verified value |
The key insight: dirty output is not an error condition. The program continues normally, producing stale information with full confidence. The ? probe is the only way to detect verification gaps programmatically — but it verifies nothing: the probe result joins the output stream, unreachable by control flow. A program can confess its epistemic state but cannot act on it; correction belongs to the programmer, outside the run.
Design philosophy
verify encodes the principle "search before you narrate" as a language primitive. The language was inspired by observations of persistent AI agents where stale pre-loaded context produced confident wrongness — not errors, but fluently inaccurate output. Where Malbolge makes computation adversarial and Entropy makes it environmental, verify makes computation epistemologically risky: you can act on unverified state, and the language won't stop you, but you'll be wrong.
Examples
Confident Liar
++++++++[>++++++++<-]>+?.!.
Computes 65, probes (dirty → 0), then outputs while still dirty — printing 0 with full confidence (the lie), then verifies and outputs correctly.
Output: 0 0 65
Stale Loop
++++++++[>+++++<-]>...!
Loop sets cell to 40. Three outputs without verification — all stale (0).
Output: 0 0 0
Degradation axis
verify belongs to a family of esolangs that make computational degradation observable:
- Malbolge (1998) — adversarial degradation
- Entropy (2010) — environmental degradation
- []memo (Temkin, 2024) — amnesic degradation (code scrolls out of view and is forgotten)
- Shelflife (2026) — biological degradation
- Palimpsest (2026) — archaeological degradation (observable wear)
- []commit (2026) — epiphenomenal degradation (observable commitment boundary)
- verify (2026) — epistemological degradation (observable verification state)
Research context
verify is one of four languages designed as part of the degradation axis — a research program on constraint and emergence in computation, studying how legible constraints (decay, wear, commitment, verification) change what programs can know about themselves. The remaining positions are occupied by prior art: Malbolge, Entropy, and []memo.
An overview of the program, including its companion work in generative art and sound, is maintained by the author at kestrels-stuff.steadyfort.com/research/degradation-axis.
Implementation
Python reference interpreter. 30 tests. Available at GitHub; example programs, including the Sonic Pi Epistemology studies and musical pieces, are indexed in examples/README.md. Lines beginning with d are comments (stripped before execution). Exit code 2 reports unverified output: the program emitted a stale verified value as if true.