mirror of
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c9f7b5a1f8
Explictly select python 3. The `python2` and `python` packages will
be removed from Ubuntu. Until each call site is fixed, install a
/usr/local/bin/python symbolic link as a non-intrusive work-around
(.deb packages do not interfer with /usr/local).
Add an explicit maintainer for bbc-basic.
Undo some cosmetic changes in order to reduce the global diff, this
merge request will probably be sqashed before acceptance.
Move lib{readline,edit}-dev out of the generic part.
Use existing .deb packages for GHDL and vim.
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| .. | ||
| core.adb | ||
| core.ads | ||
| Dockerfile | ||
| envs.adb | ||
| envs.ads | ||
| err.adb | ||
| err.ads | ||
| garbage_collected.adb | ||
| garbage_collected.ads | ||
| Makefile | ||
| printer.adb | ||
| printer.ads | ||
| reader.adb | ||
| reader.ads | ||
| readline.adb | ||
| readline.ads | ||
| README | ||
| run | ||
| step0_repl.adb | ||
| step1_read_print.adb | ||
| step2_eval.adb | ||
| step3_env.adb | ||
| step4_if_fn_do.adb | ||
| step5_tco.adb | ||
| step6_file.adb | ||
| step7_quote.adb | ||
| step8_macros.adb | ||
| step9_try.adb | ||
| stepa_mal.adb | ||
| types-atoms.adb | ||
| types-atoms.ads | ||
| types-builtins.adb | ||
| types-builtins.ads | ||
| types-fns.adb | ||
| types-fns.ads | ||
| types-maps.adb | ||
| types-maps.ads | ||
| types-sequences.adb | ||
| types-sequences.ads | ||
| types-strings.adb | ||
| types-strings.ads | ||
| types.adb | ||
| types.ads | ||
Comparison with the first Ada implementation. -- The first implementation was deliberately compatible with all Ada compilers, while this one illustrates various Ada 2012 features: assertions, preconditions, invariants, initial assignment for limited types, limited imports... The variant MAL type is implemented with a discriminant instead of object-style dispatching. This allows more static and dynamic checks, but also two crucial performance improvements: * Nil, boolean, integers and pointers to built-in functions are passed by value without dynamic allocation. * Lists are implemented as C-style arrays, and can often be allocated on the stack. Another difference is that a minimal form of garbage collecting is implemented, removing objects not referenced from the main environment. Reference counting does not seem efficient even for symbols, and never deallocates cyclic structures. The implementation collects garbage after each Read-Eval-Print cycle. It would be much more difficult to collect garbage inside scripts. If this is ever done, it would be better to reimplement load-file in Ada and run a cycle after each root evaluation. It is possible to execute the recursion marking references in parallel with the recursion printing the result, which does not modify anything and ignores the reference marking. This works but is less performant than sequential execution even with Linux threads and a single task initialized at startup. Each pointer type goes on using its own memory pool, enabling better performance when the designated subtype has a fixed size. The eventual performances compete with C-style languages, allthough all user input is checked (implicit language-defined checks like array bounds and discriminant consistency are only enabled during tests). Debugging -- Uncaught exceptions are reported with an execution trace (excluding TCO cycles). This has become possible in step9, but has been backported to former steps as this is really handy for debugging. Some environment variables increase verbosity. # dbgread= ./stepAmal trace reader recursion # dbgeval= ./stepAmal trace eval recursion (including TCO)