std.Io.print/println take any mix of printable arguments (compiler expands per type); docs, conformance

2 files changed, 40 insertions, 6 deletions

diff --git a/src/compiler/expr.zc b/src/compiler/expr.zc
index a6cc55c..2cb36cf 100644
--- a/src/compiler/expr.zc
+++ b/src/compiler/expr.zc
@@ -409,9 +409,42 @@ int shifthint(int p, int v) {
 //      function isn't defined yet)
 //   6. the result's type and class are set: .u functions return C_FRESH, which
 //      is how the analyzer knows the caller now owns a new object
+// std.Io.print(a, b, ...) and println: any mix of strings, byte strings,
+// numbers and floats. each argument goes to the writer for its type; a fresh
+// owned string is written and then freed. println ends with a line break.
+int printcall(int line) {
+	int c; char* w;
+	expect(s_lp);
+	if (!is_op(s_rp)) {
+		while (1) {
+			c = expr(); rval();
+			if (xty == tbstr || xstr) w = "std.Io.put_bs";
+			else if (xfloat) w = "std.Io.put_f";
+			else if (xty[0] == TY_PTR && xty[4] == tchar) w = "std.Io.put_s";
+			else if (xty[0] == TY_ARR && xty[4] == tchar) w = "std.Io.put_s";
+			else w = "std.Io.put_n";
+			if (c == C_FRESH && fchk) {
+				if (!rt.eq_w(w, "std.Io.put_s") && !rt.eq_w(w, "std.Io.put_bs")) cerr("a new object can't be printed; bind it to a name first");
+				lit(0); op(O_PICK); callname(intern(w)); op(O_DROP); callname(s_free); op(O_DROP);
+			} else {
+				if (c >= C_VAR && tracked(c - C_VAR)) touch(c - C_VAR);
+				callname(intern(w)); op(O_DROP);
+			}
+			if (!accept(s_comma)) break;
+		}
+	}
+	expect(s_rp);
+	if (line) { lit(10); callname(intern("rt.put_c")); op(O_DROP); }
+	lit(0);
+	lv = 0; lvk = LV_NONE; xty = tint; xzero = 0; xbor = -1; xconst = 0;
+	xfloat = 0; xstr = 0; xlenloc = -1; xstamp = 0; xaf = 0;
+	return C_PLAIN;
+}
 int call(int s) {
 	int np, tags = 0, ret = 0; word ft = stype[s]; word[8] bs; int rs, rhs_type = 0, kop, cp = callpos, original = s; word storage; int origin, temporary, owner; word origins, owner_fact;
 	word requirements = effect_requirements, edges = effect_edges;
+ if (rt.eq_w(sname[s], "std.Io.print")) return printcall(0);
+ if (rt.eq_w(sname[s], "std.Io.println")) return printcall(1);
  borrow_depth++;
 	if (sname[s] == s_new && skind[s] == K_FN) {
 		peek();
diff --git a/src/lib/std.zc b/src/lib/std.zc
index b206888..5c86aa6 100644
--- a/src/lib/std.zc
+++ b/src/lib/std.zc
@@ -421,15 +421,16 @@ struct Host {
 // called as std.Io.name(args). the writers go through rt.put_c, so a capture
 // (std.capture) sees their text too. the rt names (rt.put_n, rt.put_s and the
 // rest) stay; these are the same operations, grouped with the library.
-// zc has no varargs or overloading, so print takes a string, and numbers have
-// their own writers: std.Io.print("n = "); std.Io.put_n(n); std.Io.nl();
+// print and println take any mix of strings, byte strings, numbers and floats,
+// each written by its type: std.Io.println("n = ", n, ", x = ", x);
 struct Io {
-	// writes a string.
-	//   s: the text
+	// writes its arguments in order: any mix of strings, byte strings, numbers
+	// and floats (the compiler picks the writer for each argument's type).
+	//   s: the first value; more may follow
 	//   returns: 0
 	static int print(char* s) { return rt.put_s(s); }
-	// writes a string and a line break.
-	//   s: the text
+	// writes its arguments like print, then a line break. no arguments: just the line break.
+	//   s: the first value; more may follow
 	//   returns: 0
 	static int println(char* s) { rt.put_s(s); return rt.put_c(10); }
 	// writes a line break.