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Monorepo for Aesthetic.Computer aesthetic.computer
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100/* tinylisp.c with NaN boxing by Robert A. van Engelen 2022 */#include <stdlib.h>#include <stdio.h>#include <string.h>#define I unsigned#define L double#define T(x) *(unsigned long long*)&x>>48#define A (char*)cell#define N 1024I hp=0,sp=N,ATOM=0x7ff8,PRIM=0x7ff9,CONS=0x7ffa,CLOS=0x7ffb,NIL=0x7ffc;L cell[N],nil,tru,err,env;L box(I t,I i) { L x; *(unsigned long long*)&x = (unsigned long long)t<<48|i; return x; }I ord(L x) { return *(unsigned long long*)&x; }L num(L n) { return n; }I equ(L x,L y) { return *(unsigned long long*)&x == *(unsigned long long*)&y; }L atom(const char *s) { I i = 0; while (i < hp && strcmp(A+i,s)) i += strlen(A+i)+1; if (i == hp && (hp += strlen(strcpy(A+i,s))+1) > sp<<3) abort(); return box(ATOM,i);}L cons(L x,L y) { cell[--sp] = x; cell[--sp] = y; if (hp > sp<<3) abort(); return box(CONS,sp); }L car(L p) { return (T(p)&~(CONS^CLOS)) == CONS ? cell[ord(p)+1] : err; }L cdr(L p) { return (T(p)&~(CONS^CLOS)) == CONS ? cell[ord(p)] : err; }L pair(L v,L x,L e) { return cons(cons(v,x),e); }L closure(L v,L x,L e) { return box(CLOS,ord(pair(v,x,equ(e,env) ? nil : e))); }L assoc(L v,L e) { while (T(e) == CONS && !equ(v,car(car(e)))) e = cdr(e); return T(e) == CONS ? cdr(car(e)) : err; }I not(L x) { return T(x) == NIL; }I let(L x) { return !not(x) && !not(cdr(x)); }L eval(L,L),parse();L evlis(L t,L e) { return T(t) == CONS ? cons(eval(car(t),e),evlis(cdr(t),e)) : T(t) == ATOM ? assoc(t,e) : nil; }L f_eval(L t,L e) { return eval(car(evlis(t,e)),e); }L f_quote(L t,L _) { return car(t); }L f_cons(L t,L e) { return t = evlis(t,e),cons(car(t),car(cdr(t))); }L f_car(L t,L e) { return car(car(evlis(t,e))); }L f_cdr(L t,L e) { return cdr(car(evlis(t,e))); }L f_add(L t,L e) { L n = car(t = evlis(t,e)); while (!not(t = cdr(t))) n += car(t); return num(n); }L f_sub(L t,L e) { L n = car(t = evlis(t,e)); while (!not(t = cdr(t))) n -= car(t); return num(n); }L f_mul(L t,L e) { L n = car(t = evlis(t,e)); while (!not(t = cdr(t))) n *= car(t); return num(n); }L f_div(L t,L e) { L n = car(t = evlis(t,e)); while (!not(t = cdr(t))) n /= car(t); return num(n); }L f_int(L t,L e) { L n = car(evlis(t,e)); return n<1e16 && n>-1e16 ? (long long)n : n; }L f_lt(L t,L e) { return t = evlis(t,e),car(t) - car(cdr(t)) < 0 ? tru : nil; }L f_eq(L t,L e) { return t = evlis(t,e),equ(car(t),car(cdr(t))) ? tru : nil; }L f_pair(L t,L e) { L x = car(evlis(t,e)); return T(x) == CONS ? tru : nil; }L f_or(L t,L e) { L x = nil; while (!not(t) && not(x = eval(car(t),e))) t = cdr(t); return x; }L f_and(L t,L e) { L x = tru; while (!not(t) && !not(x = eval(car(t),e))) t = cdr(t); return x; }L f_not(L t,L e) { return not(car(evlis(t,e))) ? tru : nil; }L f_cond(L t,L e) { while (!not(t) && not(eval(car(car(t)),e))) t = cdr(t); return eval(car(cdr(car(t))),e); }L f_if(L t,L e) { return eval(car(cdr(not(eval(car(t),e)) ? cdr(t) : t)),e); }L f_leta(L t,L e) { for (;let(t); t = cdr(t)) e = pair(car(car(t)),eval(car(cdr(car(t))),e),e); return eval(car(t),e); }L f_lambda(L t,L e) { return closure(car(t),car(cdr(t)),e); }L f_define(L t,L e) { env = pair(car(t),eval(car(cdr(t)),e),env); return car(t); }struct { const char *s; L (*f)(L,L); } prim[] = {{"eval", f_eval },{"car",f_car},{"-",f_sub},{"<", f_lt },{"or", f_or },{"cond",f_cond},{"lambda",f_lambda},{"quote",f_quote},{"cdr",f_cdr},{"*",f_mul},{"int",f_int},{"and",f_and},{"if", f_if },{"define",f_define},{"cons", f_cons },{"+", f_add},{"/",f_div},{"eq?",f_eq },{"not",f_not},{"let*",f_leta},{"pair?", f_pair },{0}};L bind(L v,L t,L e) { return not(v) ? e : T(v) == CONS ? bind(cdr(v),cdr(t),pair(car(v),car(t),e)) : pair(v,t,e); }L reduce(L f,L t,L e) { return eval(cdr(car(f)),bind(car(car(f)),evlis(t,e),not(cdr(f)) ? env : cdr(f))); }L apply(L f,L t,L e) { return T(f) == PRIM ? prim[ord(f)].f(t,e) : T(f) == CLOS ? reduce(f,t,e) : err; }L eval(L x,L e) { return T(x) == ATOM ? assoc(x,e) : T(x) == CONS ? apply(eval(car(x),e),cdr(x),e) : x; }char buf[40],see = ' ';void look() { int c = getchar(); see = c; if (c == EOF) exit(0); }I seeing(char c) { return c == ' ' ? see > 0 && see <= c : see == c; }char get() { char c = see; look(); return c; }char scan() { int i = 0; while (seeing(' ')) look(); if (seeing('(') || seeing(')') || seeing('\'')) buf[i++] = get(); else do buf[i++] = get(); while (i < 39 && !seeing('(') && !seeing(')') && !seeing(' ')); return buf[i] = 0,*buf;}L Read() { return scan(),parse(); }L list() { L x; return scan() == ')' ? nil : !strcmp(buf, ".") ? (x = Read(),scan(),x) : (x = parse(),cons(x,list())); }L quote() { return cons(atom("quote"),cons(Read(),nil)); }L atomic() { L n; int i; return sscanf(buf,"%lg%n",&n,&i) > 0 && !buf[i] ? n : atom(buf); }L parse() { return *buf == '(' ? list() : *buf == '\'' ? quote() : atomic(); }void print(L);void printlist(L t) { for (putchar('('); ; putchar(' ')) { print(car(t)); if (not(t = cdr(t))) break; if (T(t) != CONS) { printf(" . "); print(t); break; } } putchar(')');}void print(L x) { if (T(x) == NIL) printf("()"); else if (T(x) == ATOM) printf("%s",A+ord(x)); else if (T(x) == PRIM) printf("<%s>",prim[ord(x)].s); else if (T(x) == CONS) printlist(x); else if (T(x) == CLOS) printf("{%u}",ord(x)); else printf("%.10lg",x);}void gc() { sp = ord(env); }int main() { I i; printf("tinylisp"); nil = box(NIL,0); err = atom("ERR"); tru = atom("#t"); env = pair(tru,tru,nil); for (i = 0; prim[i].s; ++i) env = pair(atom(prim[i].s),box(PRIM,i),env); while (1) { printf("\n%u>",sp-hp/8); print(eval(Read(),env)); gc(); }}