I-Lang v3.0 Specification

1. Overview

I-Lang is an AI-native communication protocol built from symbols already inside every LLM's training data: brackets, pipes, arrows, key-value pairs. It defines a formal vocabulary for three communication modes:

2. Two Syntaxes

2.1 Operation Syntax — What AI Does

[VERB:@TARGET|modifier=value]=>[NEXT_VERB]=>[Ω]

Operations are executable instructions. Each step in a chain receives the output of the previous step. The chain terminates with [Ω] or [OUT].

Components:

2.2 Declaration Syntax — What AI Is

::GENE{trait_name|conf:confirmed|scope:global}
  T:positive_trait
  A:anti_pattern⇒consequence
::STATE{@SELF, attribute:value}

Declarations define behavioral identity — personality, rules, anti-patterns, and immune responses. They can persist across sessions when stored in profile or configuration files.

3. Verb Categories

Total: 88 verbs. Full definitions with examples: Dictionary →

4. Greek Aliases

13 commonly-used verbs have single-character Greek aliases for maximum compression:

5. Modifiers

5.1 Core Modifiers

Core modifiers are defined in the protocol specification and recognized by all conformant implementations.

5.2 Extended Modifiers

Extended modifiers are verb-specific parameters defined in the Dictionary. They follow the same key=value syntax but are only meaningful for specific verbs.

5.3 Modifier Grammar

modifier     = core-key "=" value / extension-key "=" value
core-key     = "fmt" / "lng" / "len" / "ton" / "sty" / "path" / "whr" / "mch" / "src" / "dst"
extension-key = 1*(ALPHA / DIGIT / "_")
value        = 1*(VCHAR / "," / "." / "/" / ":" / "-" / "_" / "*" / ">" / "<" / "=")

6. Entities

6.1 Core Entities

6.2 External Entities

7. Grammar (ABNF-style)

; === Operation Syntax ===
chain        = step *("=>" step)
step         = "[" verb-call "]"
verb-call    = VERB [":" target] ["|" modifiers]
VERB         = 2*5(ALPHA)                    ; e.g., READ, FMT, OUT
target       = "@" entity-name               ; e.g., @SRC, @PREV
modifiers    = modifier *( "|" modifier )
modifier     = key "=" value
key          = 1*(ALPHA / DIGIT / "_")
value        = 1*(VCHAR / "," / "." / "/" / ":" / "-" / "_" / "*" / ">" / "<" / "=")
entity-name  = 1*(ALPHA / DIGIT / "_")

; === Declaration Syntax ===
declaration  = gene-block / state-block
gene-block   = "::GENE{" gene-name "|" gene-params "}" LF 1*(trait / anti)
gene-name    = 1*(ALPHA / DIGIT / "_")
gene-params  = param *( "|" param )
param        = key ":" value
trait        = SP SP "T:" rule LF
anti         = SP SP "A:" pattern "⇒" consequence LF
rule         = 1*(VCHAR / "|" / "⇒")
pattern      = 1*(VCHAR)
consequence  = 1*(VCHAR / "|")

state-block  = "::STATE{" target ", " 1*(key ":" value *("," key ":" value)) "}"

8. JSON AST

I-Lang chains can be represented as JSON AST for machine processing, validation, and interoperability with MCP/A2A.

{
  "type": "chain",
  "version": "3.0",
  "steps": [
    {
      "verb": "READ",
      "target": "@SRC",
      "modifiers": { "path": "sales.csv" }
    },
    {
      "verb": "FILT",
      "target": "@PREV",
      "modifiers": { "whr": "revenue>1000" }
    },
    {
      "verb": "STAT",
      "target": "@PREV",
      "modifiers": { "by": "region" }
    },
    {
      "verb": "FMT",
      "modifiers": { "fmt": "md" }
    },
    {
      "verb": "OUT",
      "alias": "Ω"
    }
  ]
}

Declaration AST:

{
  "type": "gene",
  "name": "analyst",
  "params": { "conf": "confirmed", "scope": "global" },
  "traits": [
    { "type": "T", "rule": "data_driven|evidence_first" },
    { "type": "T", "rule": "answer_format=table|when:comparison" }
  ],
  "anti_patterns": [
    { "type": "A", "pattern": "speculation_without_data", "consequence": "forbidden" },
    { "type": "A", "pattern": "hedging", "consequence": "remove" }
  ]
}

9. Error Model

10. Execution Semantics

10.1 Chain execution

Steps in a chain execute left to right. The output of each step becomes the implicit @PREV input to the next step. If a step specifies an explicit target, it overrides @PREV.

10.2 Entity resolution

Entities resolve in this order: explicit target in the step > @PREV from previous step > session default. External entities (@GH, @R2, etc.) require runtime-level configuration.

10.3 Declaration persistence

::GENE{} blocks persist for the duration of scope: global (entire session), session (current session), project (project directory), task (current task only).

10.4 Priority resolution

When multiple ::GENE{} blocks apply, priority determines order: P0 > P1 > P2. Within the same priority, more specific scope wins (task > project > session > global).

11. Security Model

I-Lang classifies verbs into three risk levels: safe (read-only, no side effects), guarded (modifies state, requires confirmation), and dangerous (data loss or code execution risk, requires explicit authorization). See the full security model for verb classifications and runtime requirements.

12. Versioning

13. Examples

# Read CSV, filter rows, sort, output as markdown table
[READ:@SRC|path=sales.csv]=>[φ|whr=revenue>1000]=>[∇|by=revenue,desc]=>[FMT|fmt=md]=>[Ω]

# Translate previous output to Japanese, formal tone
[θ:@PREV|lng=ja,ton=formal]=>[Ω]

# Batch read all markdown files, merge, summarize
[LIST:@LOCAL|mch=*.md]=>[Π:READ]=>[Σ]=>[SHRT|len=5,sty=bullets]=>[Ω]

# Define behavioral DNA for an AI agent
::GENE{analyst|conf:confirmed|scope:global}
  T:data_driven|evidence_first
  T:answer_format=table|when:comparison
  A:speculation_without_data⇒forbidden
  A:hedging⇒remove

14. Full Specification

The complete, machine-readable specification is available at:

github.com/ilang-ai/ilang-spec  ·  npm: @i-language/spec  ·  HuggingFace

Related pages: Benchmark · Conformance · Security

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