EB Language Specification

A domain-specific language for Monte Carlo simulation and stochastic modeling. One language expresses periodic, event, and agent models, and the compiler reduces all three to a single event-segment kernel.

This specification is self-contained. It supersedes the specification in ~/proj/eichenbank-claude/spec, which is frozen as reference — see Provenance.

What is normative

eb.ebnf	Grammar, keyword list, intrinsic list. The source of truth for syntax.
Semantic Rules	The numbered rules. The source of truth for behavior.
Constraints	Normative, but derived: it restates the rules per execution unit and adds none.
Error Catalog	Normative message text. The catalog is generated from tests/suite.
Usage	The command-line interface.
Design Rationale	Non-normative. Why the rules are what they are, including decisions since reversed.
Provenance	Non-normative. What changed from the eichenbank-claude spec, and why.

Where this specification and spec/eb.ebnf disagree with any older document, these win. The executable suite in tests/suite pins the behavior, and ./mk spec checks that every rule cited by a test or by a source comment actually exists here.

Reading order

For the language itself, read the grammar, then Semantic Rules. For “can I do this here?”, Constraints answers faster. For a specific diagnostic, Error Catalog.

• Grammar
• Semantic Rules
  • Agents
  • Resource Claims
  • Context Values
  • Declaration and Assignment
  • Determinism
  • Events
  • Execution Model
  • Functions
  • Group Declarations
  • Guards
  • History Access
  • If Statements
  • Init Block
  • Intrinsics
  • Periodic Items
  • Import and Export
  • Model
  • Observations
  • Resources
  • Scenarios
  • Scheduling and Control
  • Scoping
  • State Variables
  • Timing
  • Types
  • Zero Values
• Constraints
  • Periodic items (pi)
  • Events (event)
  • Agents (agent)
  • Functions (fn)
  • Init block (init)
  • Exec section
  • Cross-cutting rules
  • Why the constraints exist
• Error Catalog
  • Diagnostics
  • Phases
  • Exit codes
  • Constant versus runtime detection
  • The catalog
  • Scanner Errors
  • Parser Errors
  • Semantic Errors
  • Runtime Errors
• Usage
  • Commands
  • Optimization flags
  • Output and diagnostics
• Design Rationale
  • Two program modes: imperative and simulation
  • Intrinsics hide simulation algorithms so modelers focus on the model
  • Determinism: FIFO ordering, IEEE 754 exact comparison, no epsilon
  • Per-run PRNG reseed via a keyed-hash derivation (DET-30, EXEC-30)
  • Static scalar types, no aggregates
  • Agents as processes alongside event handlers
  • Suspension never below a call frame: agents without coroutines
  • claim and release are separate statements
  • resource as declaration keyword; rsc as the type name
  • timeout, claim, and init have no colon prefix
  • init block for lazy agent spawning
  • pi has no end; the asymmetry is intentional
  • duration as maximum simulation time
  • Functions receive periodic item values as parameters, not by name (FN-35)
  • Group declarations: shared body, N independent state records
  • sched arguments instead of event group declarations
  • FIFO wait queue for resource claims
• Provenance
  • Keywords renamed
  • Syntax changes from the old specification
  • Semantic changes from the old specification
  • Corrections to the old specification
  • What was not carried across

Implementation status

The specification leads the implementation in places. Every such place carries a NOT YET IMPLEMENTED admonition in the text; they are collected here.

:capacity(r, n)	RC-60 and RC-70 are specified; the intrinsic is not implemented.
Modules (MOD-i)	import, export, as are reserved words the compiler rejects.
sm samplers	Reserved. Per-sampler PRNG streams keyed (simseed, sampler, run).
eb repl	Reserved; reports “not yet implemented”.
Native and GPU emitters	--format native and --target are reserved. --format ebc and the VM are the supported path.
-O0 .. -O3	Parsed and ignored; all four produce identical output.
Non-integer pi periods	Rejected. See the OPEN ISSUE under PI-15.

:capacity is the one entry where the specification was changed ahead of the compiler by decision rather than by backlog: RC-60 and RC-70 are settled, and the test suite has nothing to say about them yet. The rest are ordinary “not built”.

Explicit release was in this position and no longer is — the compiler implements CLAIM-10 through CLAIM-70, and tests/suite covers crossing lifetimes, reuse through the scan, reclamation at agent termination, and the two runtime errors.