L3: RAM arrays for DVM-BASIC (fixes #106, stacks on #103) - #107
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L3: RAM arrays for DVM-BASIC (fixes #106, stacks on #103)#107liqdmetal wants to merge 5 commits into
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…F/ELSE/ENDIF
Replaces GOTO-only spaghetti with structured loops and blocks (spec
dero-improvements-agenda.md L1, P0). Halves contract size, cuts the
len(scdata)*1.5 code-size fee term, makes contracts auditable.
New dvm/control_flow.go:
- FOR var = start TO end [STEP step] / NEXT var — counter loop, step
default 1, nested frames via the interpreter's Loops stack
- WHILE expr / WEND — pre-tested loop, jumps back to the WHILE line
- block IF expr THEN ... [ELSE ...] ENDIF — detected as the line ending
in THEN without GOTO (existing single-line IF THEN GOTO untouched)
- LoopFrame stack on DVM_Interpreter for nesting (FOR-in-WHILE verified)
- findMatchingLine scans forward for WEND/ENDIF respecting nesting
Consensus-safety:
- ALL new keywords gated on DVM version >= 10.0.0 (contract must call
version("10.0.0")); pre-fork contracts cannot accidentally use them
- no parser changes — the line-token interpreter dispatches the new
keywords natively
Tests (dvm/control_flow_test.go, 8 cases):
- FOR/NEXT sum(1..5)=15, FOR/STEP 0+2+4=6, WHILE countdown=10 iterations,
block IF/ELSE both branches, IF-no-ELSE fall-through, nested FOR-in-WHILE
total=9, version gate (1.2.3 rejected), no-version gate (0.0.0 rejected)
Full dvm suite green, whole tree builds.
…F/ELSE/ENDIF
Replaces GOTO-only spaghetti with structured loops and blocks (spec
dero-improvements-agenda.md L1, P0). Halves contract size, cuts the
len(scdata)*1.5 code-size fee term, makes contracts auditable.
New dvm/control_flow.go:
- FOR var = start TO end [STEP step] / NEXT var — counter loop, step
default 1, nested frames via the interpreter's Loops stack
- WHILE expr / WEND — pre-tested loop, jumps back to the WHILE line
- block IF expr THEN ... [ELSE ...] ENDIF — detected as the line ending
in THEN without GOTO (existing single-line IF THEN GOTO untouched)
- LoopFrame stack on DVM_Interpreter for nesting (FOR-in-WHILE verified)
- findMatchingLine scans forward for WEND/ENDIF respecting nesting
Consensus-safety:
- ALL new keywords gated on DVM version >= 10.0.0 (contract must call
version("10.0.0")); pre-fork contracts cannot accidentally use them
- no parser changes — the line-token interpreter dispatches natively
Tests (dvm/control_flow_test.go, 8 cases): FOR sum, FOR/STEP, WHILE
countdown, block IF/ELSE, IF-no-ELSE fall-through, nested FOR-in-WHILE,
version gate (1.2.3), no-version gate (0.0.0). All green.
Also carries the build-manifest fix (go.mod/go.sum) for fresh-clone builds.
The second P0 language item (spec dero-improvements-agenda.md L2): internal
subroutines so entrypoints stop re-implementing helpers.
GOSUB <line>: pushes the return address (the line after the GOSUB) onto
the interpreter's CallStack and jumps to <line>.
RETURN: when CallStack is non-empty, pops it and jumps back (subroutine
return — value ignored, subroutines communicate via shared Locals);
otherwise behaves exactly as today (function return). Fully
backward-compatible: existing contracts never push a CallStack.
Gated on DVM version >= 10.0.0 like L1 (contract must call
version("10.0.0")). Nests correctly (GOSUB-in-GOSUB, GOSUB-in-FOR).
Tests (dvm/control_flow_l2_test.go, 5 cases):
- TestL2_Gosub: shared-Locals helper (x*2)
- TestL2_NestedGosub: 1 + 10 = 11 via nested calls
- TestL2_GosubInFor: helper inside FOR body, 1+2+3 = 6
- TestL2_FunctionReturnStillWorks: plain RETURN unaffected
- TestL2_VersionGate: GOSUB at 1.2.3 rejected
Stacks on L1 (feature/dvm-l1-control-flow-pr, PR DEROFDN#101).
First-class array semantics for DVM-BASIC (spec dero-improvements-agenda.md
L3, P1): DIM a(n) AS Uint64|String creates a zero-filled RAM array
(indices 0..n, cap 1024); a[i] reads via the evaluator's new IndexExpr
case; LET a[i] = expr writes (index may be a literal or expression like a
loop variable); arrlen("a") returns the length.
Design:
- Variable gains Array *[]Variable (pointer keeps Variable comparable —
it is used as a map key in RamStore/SC state)
- Arrays are Locals-only: contracts cannot STORE an array (STORE takes
scalars), so nothing touches the serialized SC state — consensus-neutral
- gated >= 10.0.0 like L1/L2 (contract must call version("10.0.0"))
- composes with L1: FOR i = 0 TO n / a[i] = ... / NEXT i
Tests (dvm/control_flow_l3_test.go, 4 cases): array basics (set/read/
arrlen), FOR-loop fill (sum of squares 0..10 = 385), string arrays,
version gate (1.2.3 rejected).
Full dvm suite green. Stacks on L2 (feature/dvm-l2-subroutines, PR DEROFDN#103).
This was referenced Aug 23, 2026
…ndor) Same two fixes as the sibling PRs: remove the l.Operation.KickReader() calls (no published chzyer/readline implements it) and re-vendor with a proper modules.txt. Fresh-clone go build now succeeds without -mod=mod.
Author
|
Superseded by PR #126 — the consolidated language package. Same code, one reviewable PR with no vendor noise. |
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Summary
L3 from the DVM-BASIC language agenda (P1): first-class RAM arrays —
DIM a(n) AS type,a[i]get/set,arrlen. Gives contracts list semantics instead of hand-rolled scalar keys, and composes with L1'sFORloops for iteration.The syntax
With L1's FOR:
Implementation
VariablegainsArray *[]Variable— a pointer so Variable stays comparable (it's used as a map key inRamStore/SC state; a raw slice would break compilation).DIM a(n) AS Uint64|String— detects the( n )form ininterpret_DIM, allocatesn+1zero-filled elements, cap 1024.a[i]read — new*ast.IndexExprcase in the evaluator (Go's parser already tokenizesa [ i ]).LET a[i] = expr— new branch ininterpret_LET; the index is evaluated (literal or expression like a loop variable), with bounds checking.arrlen("a")— intrinsic returning the length, gated>= 10.0.0.Consensus safety
STOREan array (STORE takes scalars), so arrays never touch the serialized SC state — consensus-neutral (no state-format change).>= 10.0.0like L1/L2 — pre-fork contracts can't use it.Tests (
dvm/control_flow_l3_test.go, 4 cases)TestL3_ArrayBasicsarrlenTestL3_ArrayForLoopTestL3_StringArrayTestL3_VersionGateDIM a(n)at1.2.3rejectedFull dvm suite green.
Relationship
>= 10.0.0gate and interpreter machinerymapkeysa natural return typeBranch:
feature/dvm-l3-arraysin the forkliqdmetal/derohe-improvements-by-liqdmetal(stacked onfeature/dvm-l2-subroutines).