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Enhanced High Level Lisp prototype with Lexical scope and Let Expressions

This commit is contained in:
Jeremiah Orians 2017-05-14 12:21:31 -04:00
parent 2785f8b59f
commit fd70c64f07
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GPG Key ID: 7457821534D2ACCD
3 changed files with 33 additions and 7 deletions
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2
CHANGELOG.org
View File

@ -17,8 +17,10 @@
* Current
** Added
Added absolute addresses to High level assembler output to aid in debugging of complex assembly programs
Added Let expressions to High Level prototype lisp
** Changed
Converted High level prototype lisp from dynamic scope to Lexical
** Fixed
Made Web debugger provide more useful information

13
stage2/High_level_prototypes/lisp.h
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@ -55,5 +55,16 @@ typedef struct cell
struct cell* make_cons(struct cell* a, struct cell* b);
/* Global objects */
struct cell *all_symbols, *top_env, *nil, *tee, *quote, *s_if, *s_lambda, *s_define, *s_setb, *s_cond, *s_begin;
struct cell *all_symbols;
struct cell *top_env;
struct cell *nil;
struct cell *tee;
struct cell *quote;
struct cell *s_if;
struct cell *s_lambda;
struct cell *s_define;
struct cell *s_setb;
struct cell *s_cond;
struct cell *s_begin;
struct cell *s_let;
FILE* output;

25
stage2/High_level_prototypes/lisp_eval.c
View File

@ -57,9 +57,10 @@ struct cell* multiple_extend(struct cell* env, struct cell* syms, struct cell* v
return multiple_extend(extend(env, syms->car, vals->car), syms->cdr, vals->cdr);
}
struct cell* extend_top(struct cell* sym, struct cell* val)
struct cell* extend_env(struct cell* sym, struct cell* val, struct cell* env)
{
top_env->cdr = make_cons(make_cons(sym, val), top_env->cdr);
env->cdr = make_cons(env->car, env->cdr);
env->car = make_cons(sym, val);
return val;
}
@ -86,10 +87,9 @@ struct cell* progn(struct cell* exps, struct cell* env)
{
if(exps == nil) return nil;
struct cell* result;
for(;;)
{
struct cell* result;
result = eval(exps->car, env);
if(exps->cdr == nil) return result;
exps = exps->cdr;
@ -105,7 +105,8 @@ struct cell* apply(struct cell* proc, struct cell* vals)
}
else if(proc->type == PROC)
{
temp = progn(proc->cdr, multiple_extend(proc->env, proc->car, vals));
struct cell* env = make_cons(proc->env->car, proc->env->cdr);
temp = progn(proc->cdr, multiple_extend(env, proc->car, vals));
}
else
{
@ -180,6 +181,15 @@ struct cell* process_setb(struct cell* exp, struct cell* env)
return newval;
}
struct cell* process_let(struct cell* exp, struct cell* env)
{
for(struct cell* lets = exp->cdr->car; lets != nil; lets = lets->cdr)
{
env = make_cons(make_cons(lets->car->car, eval(lets->car->cdr->car, env)), env);
}
return progn(exp->cdr->cdr, env);
}
struct cell* process_cons(struct cell* exp, struct cell* env)
{
if(exp->car == s_if) return process_if(exp, env);
@ -187,8 +197,9 @@ struct cell* process_cons(struct cell* exp, struct cell* env)
if(exp->car == s_begin) return progn(exp->cdr, env);
if(exp->car == s_lambda) return make_proc(exp->cdr->car, exp->cdr->cdr, env);
if(exp->car == quote) return exp->cdr->car;
if(exp->car == s_define) return(extend_top(exp->cdr->car, eval(exp->cdr->cdr->car, env)));
if(exp->car == s_define) return(extend_env(exp->cdr->car, eval(exp->cdr->cdr->car, env), env));
if(exp->car == s_setb) return process_setb(exp, env);
if(exp->car == s_let) return process_let(exp, env);
return apply(eval(exp->car, env), evlis(exp->cdr, env));
}
@ -466,6 +477,7 @@ void init_sl3()
s_define = make_sym("define");
s_setb = make_sym("set!");
s_begin = make_sym("begin");
s_let = make_sym("let");
/* Globals of interest */
all_symbols = make_cons(nil, nil);
@ -480,6 +492,7 @@ void init_sl3()
spinup(s_define, s_define);
spinup(s_setb, s_setb);
spinup(s_begin, s_begin);
spinup(s_let, s_let);
/* Add Primitive Specials */
spinup(make_sym("+"), make_prim(prim_sum));