c_stmt -- returns 1 if it left a value on the stack, 0 if not:

fn c_stmt() i64 {
    if (is_letter(cur()) == 1) {
        var save: i64 = src_pos;
        var word: i64 = read_name();

        if (streq_mem(word, "var") == 1 or streq_mem(word, "const") == 1) {
            var vname: i64 = read_name();
            if (cur() == ':') { src_pos += 1; skip(); read_name(); }
            if (cur() == '=') { src_pos += 1; skip(); }
            c_expression();
            if (is_global(vname) == 1) { emit_s("  global.set $"); }
            else { emit_s("  local.set $"); }
            emit_s(vname); emit_byte('\n');
            if (cur() == ';') { src_pos += 1; skip(); }
            return 0;
        }

        if (streq_mem(word, "return") == 1) {
            c_expression();
            emit_s("  return\n");
            if (cur() == ';') { src_pos += 1; skip(); }
            return 0;
        }

        if (streq_mem(word, "if") == 1) {
            if (cur() == '(') { src_pos += 1; skip(); }
            c_expression();
            if (cur() == ')') { src_pos += 1; skip(); }
            emit_s("  if (result i64)\n");
            c_block();
            if (is_letter(cur()) == 1) {
                var s2: i64 = src_pos;
                var w2: i64 = read_name();
                if (streq_mem(w2, "else") == 1) {
                    emit_s("  else\n");
                    c_block();
                } else {
                    src_pos = s2;
                    emit_s("  else\n  i64.const 0\n");
                }
            } else {
                emit_s("  else\n  i64.const 0\n");
            }
            emit_s("  end\n");
            return 1;
        }

        if (streq_mem(word, "while") == 1) {
            emit_s("  block\n  loop\n");
            if (cur() == '(') { src_pos += 1; skip(); }
            c_expression();
            if (cur() == ')') { src_pos += 1; skip(); }
            emit_s("  i64.eqz\n  br_if 1\n");
            c_block();
            emit_s("  drop\n  br 0\n  end\n  end\n");
            return 0;
        }

        if (streq_mem(word, "for") == 1) {
            if (cur() == '(') { src_pos += 1; skip(); }
            c_expression();
            if (cur() == '.') { src_pos += 1; }
            if (cur() == '.') { src_pos += 1; }
            skip();
            c_expression();
            emit_s("  local.set $__for_end\n");
            if (cur() == ')') { src_pos += 1; skip(); }
            if (cur() == '|') { src_pos += 1; skip(); }
            var loop_var: i64 = read_name();
            if (cur() == '|') { src_pos += 1; skip(); }
            emit_s("  local.set $"); emit_s(loop_var); emit_byte('\n');
            emit_s("  block\n  loop\n");
            emit_s("  local.get $"); emit_s(loop_var); emit_byte('\n');
            emit_s("  local.get $__for_end\n  i64.ge_s\n  br_if 1\n");
            c_block();
            emit_s("  drop\n");
            emit_s("  local.get $"); emit_s(loop_var); emit_byte('\n');
            emit_s("  i64.const 1\n  i64.add\n");
            emit_s("  local.set $"); emit_s(loop_var); emit_byte('\n');
            emit_s("  br 0\n  end\n  end\n");
            return 0;
        }

        if (streq_mem(word, "break") == 1) {
            if (cur() == ';') { src_pos += 1; skip(); }
            emit_s("  br 1\n");
            return 0;
        }

        if (streq_mem(word, "fn") == 1) {
            c_fn();
            return 0;
        }

        // compound assignment: name += expr
        if (cur() == '+' and load8(src_pos + 1) == '=') {
            src_pos += 2; skip();
            if (is_global(word) == 1) { emit_s("  global.get $"); }
            else { emit_s("  local.get $"); }
            emit_s(word); emit_byte('\n');
            c_expression();
            emit_s("  i64.add\n");
            if (is_global(word) == 1) { emit_s("  global.set $"); }
            else { emit_s("  local.set $"); }
            emit_s(word); emit_byte('\n');
            if (cur() == ';') { src_pos += 1; skip(); }
            return 0;
        }
        if (cur() == '-' and load8(src_pos + 1) == '=') {
            src_pos += 2; skip();
            if (is_global(word) == 1) { emit_s("  global.get $"); }
            else { emit_s("  local.get $"); }
            emit_s(word); emit_byte('\n');
            c_expression();
            emit_s("  i64.sub\n");
            if (is_global(word) == 1) { emit_s("  global.set $"); }
            else { emit_s("  local.set $"); }
            emit_s(word); emit_byte('\n');
            if (cur() == ';') { src_pos += 1; skip(); }
            return 0;
        }

        // assignment: name = expr (not ==)
        if (cur() == '=' and load8(src_pos + 1) != '=') {
            src_pos += 1; skip();
            c_expression();
            if (is_global(word) == 1) { emit_s("  global.set $"); }
            else { emit_s("  local.set $"); }
            emit_s(word); emit_byte('\n');
            if (cur() == ';') { src_pos += 1; skip(); }
            return 0;
        }

        src_pos = save;
    }
    c_expression();
    if (cur() == ';') { src_pos += 1; skip(); }
    return 1;
}

Every keyword check uses streq_mem with string literals. var and const are handled together with or. for parses the (start..end) |name| syntax. break emits br 1. Compound assignment (+=, -=) emits get-compute-set. The = vs == check uses load8(src_pos + 1) != '='.