Cons pair support - #6
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Replace linked lists approach for expression lists with proper cons-pairs. One of my biggest/ugliest commits, but most of the files had to be changed. General changes: * The 'expr_is_nil' function now only admits symbols with a value of "nil", since there are no expressions of type "List". * Make 'expr_list_print' static, add 'print_func' argument. New functions and callable macros: * Add 'expr_is_proper_list' function. * Add 'expr_list_nth' function. * Add 'expr_list_has_only_lists' function, used in 'prim_append'. * Add 'SL_EXPECT_PROPER_LIST' callable macro. * Add 'CAR', 'CDR', 'CADR' and 'CDDR' callable macros. Renamed functions and macros: * Replace old 'EXPR_PARENT' macro with 'EXPR_PAIR'. * Replace 'EXPR_LST_P' callable macro with 'EXPR_PAIR_P'. * Rename 'expr_list_is_member' function to 'expr_is_member'. * Replace 'prim_is_list' C function (that used to check for 'EXPR_PARENT') and 'list?' Lisp function with 'prim_is_pair' and 'pair?', respectively. Removed functions: * Remove 'expr_list_clone' function, since we can now clone the a whole tree if needed with 'expr_clone_recur'. * Remove 'expr_list_equal' function. * Remove 'expr_list_write' function. * Remove 'mark_lambdactx' static function from 'garbage_collector.c'. TODO comments: * About adding a 'mapcar' C function, in 'eval_list'. * About adding a 'SL_EXPECT_LEN' callable macro, in 'SL_EXPECT_ARG_NUM'. * About renaming the argument names in C primitives, in 'SL_EXPECT_ARG_NUM'. * About adding 'TOKEN_DOT' to lexer, in 'parse_recur'. * About allowing dot inside lists to indicate the CDR, in 'parse_recur'. * About 'list?' Lisp function. Things left to do: * Allow dots when parsing lists for specifying the CDR.
Add 'TOKEN_DOT' to lexer.
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Feb 16, 2025
Work with references, instead of always returning copies. This change was possible thanks to #5 (which needed #4), #6 and #7. Some changes were merged into this 'copy-references' branch in #7. Major changes: * Remove most calls to 'expr_clone', for working with references instead of copies. * Return or store references in 'car', 'cdr', 'cons', 'nth', 'quote' and 'backquote' primitives. * Add proper environment closures, setting the parent environments whenever a lambda is created, not when it's called. See #7. * Change how GC handles lambdas, add 'is_used' member to 'Env'. Mostly included in #7, but not completely (see 5758c96). * Don't mark globals ('g_nil', 'g_tru' and 'g_debug_trace_list') for garbage collection, since their references are being stored in the environment. Minor changes: * Add 'gc_mark_env' and 'gc_mark_env_and_parents' static functions to 'garbage_collector.c'. * Add an 'Env*' parameter to 'lambdactx_init', remove it from 'lambdactx_eval_body'. * Don't make the 'Expr*' parameter of 'env_bind' and 'env_bind_global' constant. * Add closure test to 'test/lambdas.lisp'. See #7.
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Replace linked lists approach for expression lists with proper cons-pairs. Most of the files had to be changed. See my blog article for more information.
General changes:
expr_is_nilfunction now only admits symbols with a value of "nil",since there are no expressions of type "List".
expr_list_printstatic, addprint_funcargument.New functions and callable macros:
expr_is_proper_listfunction.expr_list_nthfunction.expr_list_has_only_listsfunction, used inprim_append.SL_EXPECT_PROPER_LISTcallable macro.CAR,CDR,CADRandCDDRcallable macros.Renamed functions and macros:
EXPR_PARENTmacro withEXPR_PAIR.EXPR_LST_Pcallable macro withEXPR_PAIR_P.expr_list_is_memberfunction toexpr_is_member.prim_is_listC function (that used to check forEXPR_PARENT) andlist?Lisp function withprim_is_pairandpair?, respectively.Removed functions:
expr_list_clonefunction, since we can now clone the a whole tree ifneeded with
expr_clone_recur.expr_list_equalfunction.expr_list_writefunction.mark_lambdactxstatic function fromgarbage_collector.c.TODO comments:
mapcarC function, ineval_list.SL_EXPECT_LENcallable macro, inSL_EXPECT_ARG_NUM.SL_EXPECT_ARG_NUM.TOKEN_DOTto lexer, inparse_recur.parse_recur.list?Lisp function.