Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 23:53:56 -04:00
# CLAUDE.md
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
This file provides guidance to Claude Code (claude.ai/code) when working with code in this
repository.
Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 23:53:56 -04:00
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
## Read MAINTENANCE.md first
Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 23:53:56 -04:00
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
**[`MAINTENANCE.md` ](MAINTENANCE.md ) is the authoritative document for changing this project**,
and it is written for whoever has to do the changing — human or agent. It carries what used to
live in this file: the project goals, the Go reference implementation and its architecture, the
dependency versions and their ABI rules, the four ways an embedded build collides, the
`libakerror` error convention, the coordinated error-code range map, the test lists, the
documentation-example harness, and the style and commit rules.
Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 23:53:56 -04:00
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
There is one copy of all of that, on purpose. Anything you would have added here, add there
instead — the maintainer needs it as much as you do, and a second copy is a second thing to
keep true.
2026-07-31 12:52:00 -04:00
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
`akbasic` is a C rewrite of the Go BASIC interpreter in `deps/basicinterpret` , written in the
idiom of the `ak*` C libraries it builds on, and meant to end up embedded in `libakgl` as a
scripting engine for game authors.
Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 23:53:56 -04:00
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
| Read | For |
|---|---|
| [`MAINTENANCE.md` ](MAINTENANCE.md ) | Everything above. Start here |
| [`TODO.md` ](TODO.md ) | Outstanding defects, with file, line and consequence. §0.1 first — it retires the byte-for-byte fidelity constraint several later sections were written on |
| [`README.md` ](README.md ) | What the project is and why, for somebody who has not seen it |
Add two Breakout examples and the tutorials that build them
Two complete games in `examples/breakout/`, both 100% BASIC: `characters/`
draws its wall in the text grid with two `DATA` sprites for the ball and
paddle, and `sprites/` loads CC0 artwork and captures its whole screen with
`SSHAPE`/`SPRSAV`. They take opposite shapes for reasons that are entirely
this interpreter's, which is what the chapters are for.
`docs/17-tutorial-breakout.md` and `docs/18-tutorial-breakout-artwork.md`
build each one a step at a time, and end in a checklist of the rules a real
program runs into: create every name before the loop starts, write a text row
whole, loop with `GOTO` rather than `DO`, put the float on the left. Every
trap is a runnable block with its own output rather than a claim -- the value
pool dying at four thousand names, the skipped `BEGIN` block that breaks its
caller's `RETURN`, `SSHAPE` ignoring a subscript, `READ`'s single cursor.
Five figures, generated from the listings beside them by `docs_screenshots`,
and a `breakout_art` setup so the ones that load artwork load the example's
own. The character game's wall cannot be photographed -- the screenshot host
omits the text layer on purpose -- so it is shown as compared output instead.
`docs/07-sound.md` never said `SOUND`'s frequency is a SID register value
rather than hertz, which both games depend on. It says so now, with the
conversion from `src/audio_tables.c:84`.
`TODO.md` gains the thirteen defects the two games turned up -- §6 items 30
to 33 and all of §9 -- each with a reduction that fits on a screen, the file
and line of the cause, and what a fix would touch.
Verified: `docs_examples` passes in both build configurations,
`docs_screenshots --check` re-renders all thirteen figures and byte-compares
them, the full 109-test suite passes in both builds, every quoted fragment
was checked to appear verbatim in the listing it came from, and every
relative link and anchor resolves.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-01 22:54:42 -04:00
| [`docs/` ](docs/README.md ) | The language itself: eighteen chapters, verb and function reference. [Chapter 14 ](docs/14-architecture.md ) is the interpreter's architecture — the step loop, the pools, the two kinds of error, and how to debug it. [Chapter 15 ](docs/15-error-codes.md ) is the error-code appendix. [Chapters 17 ](docs/17-tutorial-breakout.md ) and [18 ](docs/18-tutorial-breakout-artwork.md ) are tutorials that build the games in `examples/breakout/` |
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
| `deps/libakerror/AGENTS.md` | The `ATTEMPT` /`CLEANUP` /`PROCESS` /`HANDLE` /`FINISH` protocol, authoritatively |
| `deps/libakerror/UPGRADING.md` | 1.0.0's status registry. Required before writing an error code |
| `deps/<library>/AGENTS.md` | Per-repo rules. Read the relevant one **before editing a submodule ** |
Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-30 23:53:56 -04:00
Before doing anything else in a fresh clone:
```sh
git submodule update --init --recursive
```
Split the documentation by who reads it
README.md was 577 lines and answered four different questions at once: what
the project is, how to build it, every verb and function in the language, and
how to maintain the test harness. The verb and function lists had already been
written a second time in docs/11 and docs/12, which is how a list of that size
goes stale -- there is no way to notice the two have drifted apart.
README.md is now 150 lines and holds only what somebody evaluating the project
needs: what it is, the quickstart, why it was rewritten in C, the five rules
embedding imposes on the design, the two ways to use it, and where everything
else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md.
The akbasic_TextSink struct moved to docs/10-embedding.md rather than being
deleted. It was the corpus's only `c excerpt=` block -- the check that caught
the stale struct two commits ago -- so dropping it with the README would have
quietly retired a test. docs/10 also stopped claiming README.md carries the
full API surface and the pool limits, which the trim made false.
CLAUDE.md went from 458 lines to 62, because almost none of it was
agent-specific. The project goals, the Go reference and its architecture, the
dependency version and ABI rules, the four ways an embedded build collides,
the libakerror convention, the error-code range map and the style rules are
all things a maintainer needs, and they are now in MAINTENANCE.md with one
copy to keep true. CLAUDE.md points there and keeps only the rules no test
enforces: tests in the same commit asserting the correct contract, file a
missing dependency capability upstream, do not edit generated output or
tests/reference/, co-author your commits.
Four claims did not survive the move, having gone stale where nothing could
notice:
- "The repository is currently empty apart from its submodules -- no
commits, no source tree, no build files." There are 43 commits.
- libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE)
at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is
gone; only a historical mention in a comment remains.
- "akbasic_init() claims 512-767." There is no akbasic_init. It is
akbasic_error_register(), called from akbasic_runtime_init().
- Time-relative phrasing ("libakgl hit two of them in the last week").
Five places pointed at CLAUDE.md for the range map or the file-it-upstream
rule and now point at MAINTENANCE.md: include/akbasic/error.h,
src/runtime_disk.c and three entries in TODO.md. Both source changes are
comments. deps/libakgl/TODO.md cites it too and is left alone; it is a
submodule, and the rule it quotes is still reachable from CLAUDE.md.
ctest is green at 95 of 95, docs_examples included: 36 programs, 9
transcripts, 44 output comparisons, 3 C snippets, 1 excerpt.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-31 22:59:43 -04:00
## Rules that are on you rather than on a test
Most of the conventions in `MAINTENANCE.md` are enforced by something — a sorted-table test, a
`WILL_FAIL` list, a Doxygen gate, a byte-compared corpus. These are not, so they are worth
repeating where you will see them:
- **Add tests in the same commit as the behaviour change**, and assert the * correct * contract
even where the code is currently wrong. A known-failing test goes in
`AKBASIC_KNOWN_FAILING_TESTS` with a `TODO.md` entry; it does not get pinned to the buggy
behaviour, because that turns the eventual fix into a test failure.
- **Never work around a missing dependency capability here.** File it in that repository's
`TODO.md` — what the BASIC verb requires, what the entry point should look like, what tests
would cover it. `MAINTENANCE.md` explains why, and names the four gaps this closed upstream.
- **Never edit generated output** — `build/` trees, the generated `akerror.h` , `akgl.pc` ,
`include/akgl/SDL_GameControllerDB.h` . Change the template or the generator script.
- **Do not reformat code you are not otherwise changing.** Several files mix tabs and spaces
and there is no repo-wide formatter; style conversions get their own commit.
- **Do not edit `tests/reference/` .** Those expectations came from the Go implementation and
are never edited to suit this interpreter. A deliberate divergence goes in `TODO.md` and
`docs/13-differences.md` .
- **Update `TODO.md` when you learn something about a defect**, including that it is worse or
better than recorded. Publishing a problem you cannot fix yet is a contribution.
- **Add yourself — program, model and version — as a commit co-author.** `libakgl` 's
`AGENTS.md` requires it and this repository follows the same rule.
