033892777a
See issue #587. * Merge eval-ast and eval into a single conditional. * Expand macros during the apply phase, removing lots of duplicate tests, and increasing the overall consistency by allowing the macro to be computed instead of referenced by name (`((defmacro! cond (...)))` is currently illegal for example). * Print "EVAL: $ast" at the top of EVAL if DEBUG-EVAL exists in the MAL environment. * Remove macroexpand and quasiquoteexpand special forms. * Use pattern-matching style in process/step*.txt. Unresolved issues: c.2: unable to reproduce with gcc 11.12.0. elm: the directory is unchanged. groovy: sometimes fail, but not on each rebuild. nasm: fails some new soft tests, but the issue is unreproducible when running the interpreter manually. objpascal: unreproducible with fpc 3.2.2. ocaml: unreproducible with 4.11.1. perl6: unreproducible with rakudo 2021.09. Unrelated changes: Reduce diff betweens steps. Prevent defmacro! from mutating functions: c forth logo miniMAL vb. dart: fix recent errors and warnings ocaml: remove metadata from symbols. Improve the logo implementation. Encapsulate all representation in types.lg and env.lg, unwrap numbers. Replace some manual iterations with logo control structures. Reduce the diff between steps. Use native iteration in env_get and env_map Rewrite the reader with less temporary strings. Reduce the number of temporary lists (for example, reverse iteration with butlast requires O(n^2) allocations). It seems possible to remove a few exceptions: GC settings (Dockerfile), NO_SELF_HOSTING (IMPLS.yml) and step5_EXCLUDES (Makefile.impls) . |
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|---|---|---|
| .. | ||
| tests | ||
| core.pm | ||
| Dockerfile | ||
| env.pm | ||
| interop.pm | ||
| Makefile | ||
| printer.pm | ||
| reader.pm | ||
| readline.pm | ||
| README.md | ||
| run | ||
| step0_repl.pl | ||
| step1_read_print.pl | ||
| step2_eval.pl | ||
| step3_env.pl | ||
| step4_if_fn_do.pl | ||
| step5_tco.pl | ||
| step6_file.pl | ||
| step7_quote.pl | ||
| step8_macros.pl | ||
| step9_try.pl | ||
| stepA_mal.pl | ||
| types.pm | ||
Notes on the mal implementation in Perl5.
This implementation should work in any perl from 5.19.3 onwards.
Earlier versions are likely to work too as long as you install a new
List::Util. The implementation uses the experimental switch
feature, which may make it vulnerable to future changes in perl.
Mal objects are all in subclasses of Mal::Type, and can be treated
as scalar, array, or hash references as appropriate.
Metadata support uses Hash::Util::FieldHash to attach external
metadata to objects. This means that in the metadata system imposes
no overhead on the normal use of objects.
Hash-maps are slightly magical. They're keyed by the stringified
versions of mal objects, and Mal::Scalar overloads stringification
so that this works properly.
Tail-call optimisation uses Perl's built-in goto &NAME syntax for
explicit tail calls. This allows functions defined by fn* to be
implemented as functions at the Perl layer.
Perl's garbage-collection is based on reference counting. This means
that reference loops will cause memory leaks, and in particular using
def! to define a function will cause that function to have a
reference to the environment it's defined in, making a small reference
loop and hence a memory leak. This can be avoided by carefully
undefining any function before it goes out of scope.