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Passing Passing: the compiler rejects this program as expected.
Code
// ============================================================================
// VERIFIED REGRESSION TEST - DO NOT MODIFY WITHOUT DISCUSSION
// ============================================================================
// Test: Template String Interpolation - THE PILLAR
// Feature: Source parameters can access their text content
// Verifies: Basic Source parameter access works
// ============================================================================
~import std/io
const std = @import("std");
// Event that takes Source[HTML] parameter for template rendering
// [comptime|transform] annotation marks this as compile-time transformation
// Transform events receive: source (user args), invocation (for context), program (AST), allocator (memory)
~[comptime|transform]tor renderHTML { source: Source<HTML>, invocation: *const Invocation, program: *const std/compiler:Program, allocator: std.mem.Allocator }
| transformed SiteResult
| failed string
~proc renderHTML|zig {
const ast = @import("ast");
const ast_functional = @import("ast_functional");
// Transform is responsible for:
// 1. Extracting HTML text from Source parameter
// 2. Creating runtime event/proc WITHOUT Source parameter
// 3. Transforming flows to remove Source argument
// 4. Filtering out comptime event
// 5. Returning complete transformed Program
// Extract HTML text from Source parameter (passed by compiler)
const html_text = source.text;
const source_location = source.location;
if (html_text.len == 0) {
return .{ .failed = "Source parameter is empty" };
}
// Generate Zig code that returns | rendered { html: []const u8 }
// Build multiline string with \\ prefix for each line
var body_parts: [4096]u8 = undefined;
var body_len: usize = 0;
const prefix = "const html =\n";
std.mem.copyForwards(u8, body_parts[body_len..], prefix);
body_len += prefix.len;
// Add each line of HTML with \\ prefix
var line_num: usize = 0;
var i_start: usize = 0;
var i_idx: usize = 0;
while (i_idx <= html_text.len) : (i_idx += 1) {
const is_newline = i_idx < html_text.len and html_text[i_idx] == '\n';
const is_end = i_idx == html_text.len;
if (is_newline or is_end) {
const line_prefix = " \\\\";
std.mem.copyForwards(u8, body_parts[body_len..], line_prefix);
body_len += line_prefix.len;
const line_text = html_text[i_start..i_idx];
std.mem.copyForwards(u8, body_parts[body_len..], line_text);
body_len += line_text.len;
body_parts[body_len] = '\n';
body_len += 1;
i_start = i_idx + 1;
line_num += 1;
}
}
const suffix = ";\nreturn .{ .rendered = .{ .html = html } };";
std.mem.copyForwards(u8, body_parts[body_len..], suffix);
body_len += suffix.len;
const proc_body = allocator.dupe(u8, body_parts[0..body_len]) catch unreachable;
// Build DottedPath for renderHTML
const path_segments = allocator.alloc([]const u8, 1) catch unreachable;
path_segments[0] = allocator.dupe(u8, "renderHTML") catch unreachable;
const renderHTML_path = ast.DottedPath{
.module_qualifier = allocator.dupe(u8, program.main_module_name) catch unreachable,
.segments = path_segments,
};
// Create runtime EventDecl (no Source parameter!)
const runtime_fields = allocator.alloc(ast.Field, 0) catch unreachable;
const runtime_event = ast.EventDecl{
.path = renderHTML_path,
.input = ast.Shape{ .fields = runtime_fields }, // No input
.branches = &[_]ast.Branch{
ast.Branch{
.name = "rendered", // String literal - always valid
.payload = ast.Shape{ .fields = &[_]ast.Field{
ast.Field{
.name = "html", // String literal - always valid
.type = "[]const u8", // String literal - always valid
.module_path = null,
.phantom = null,
.is_source = false,
.is_file = false,
},
} },
.is_optional = false,
},
},
.is_public = false,
.is_implicit_flow = false,
.annotations = &[_][]const u8{},
.is_pure = false,
.is_transitively_pure = false,
.location = source_location,
.module = allocator.dupe(u8, program.main_module_name) catch unreachable,
};
// Create runtime ProcDecl that implements renderHTML
const runtime_proc = ast.ProcDecl{
.path = renderHTML_path,
// Proc bodies are Source-typed: the synthesized proc carries the
// provenance of the Source block it was rendered from.
.body = ast.Source{ .text = proc_body, .location = source_location, .scope = .{ .bindings = &[_]ast.ScopeBinding{} }, .phantom_type = null },
.annotations = &[_][]const u8{},
.target = allocator.dupe(u8, "zig") catch unreachable,
.is_impl = true,
.location = source_location,
.module = allocator.dupe(u8, program.main_module_name) catch unreachable,
};
// Build new Program: transform flows, filter out comptime event+proc, add runtime event+proc
// Allocate array with same size (removes 2, adds 2 = net 0)
const new_items = allocator.alloc(ast.Item, program.items.len) catch unreachable;
var idx: usize = 0;
for (program.items) |prog_item| {
// Filter out comptime renderHTML event_decl
if (prog_item == .event_decl) {
const event = prog_item.event_decl;
if (event.path.segments.len == 1 and std.mem.eql(u8, event.path.segments[0], "renderHTML")) {
continue; // Skip comptime event
}
}
// Filter out comptime renderHTML proc_decl
if (prog_item == .proc_decl) {
const proc = prog_item.proc_decl;
if (proc.path.segments.len == 1 and std.mem.eql(u8, proc.path.segments[0], "renderHTML")) {
continue; // Skip comptime proc
}
}
// Transform flows that invoke renderHTML (remove Source arg)
if (prog_item == .flow) {
const flow = prog_item.flow;
// Match renderHTML with or without module qualifier
const is_renderHTML = flow.inv().path.segments.len == 1 and
std.mem.eql(u8, flow.inv().path.segments[0], "renderHTML");
if (is_renderHTML) {
// Create new invocation WITHOUT Source argument, preserving module info
const transformed_path = ast.DottedPath{
.module_qualifier = flow.inv().path.module_qualifier, // Preserve module qualifier
.segments = path_segments,
};
// Mark as already transformed to prevent infinite loops
const annotations = allocator.alloc([]const u8, 1) catch unreachable;
annotations[0] = allocator.dupe(u8, "@pass_ran(\"transform\")") catch unreachable;
const new_invocation = ast.Invocation{
.path = transformed_path,
.args = &[_]ast.Arg{}, // No arguments!
.annotations = annotations,
.inserted_by_tap = false,
.from_opaque_tap = false,
};
// Create transformed flow preserving continuations
const transformed_flow = ast.Flow{
.body = ast.rootSite(new_invocation, flow.body.continuations, flow.location), // Preserve continuations!
.annotations = flow.annotations,
.pre_label = flow.pre_label,
.super_shape = flow.super_shape,
.is_pure = flow.is_pure,
.is_transitively_pure = flow.is_transitively_pure,
.location = flow.location,
.module = flow.module,
};
new_items[idx] = ast.Item{ .flow = transformed_flow };
idx += 1;
continue;
}
}
// Modules can be shared (shallow copy), everything else needs deep copy
if (prog_item == .module_decl) {
new_items[idx] = prog_item; // Shallow copy OK for modules
} else {
new_items[idx] = ast_functional.cloneItem(allocator, &prog_item) catch unreachable;
}
idx += 1;
}
// Add runtime event and proc
new_items[idx] = ast.Item{ .event_decl = runtime_event };
new_items[idx + 1] = ast.Item{ .proc_decl = runtime_proc };
const new_program = allocator.create(ast.Program) catch unreachable;
new_program.* = ast.Program{
.items = new_items,
.module_annotations = program.module_annotations,
.main_module_name = program.main_module_name,
.allocator = allocator,
};
// This transform rebuilds the whole program (replace renderHTML + append
// runtime event/proc), so it uses the whole-program escape.
return .{ .transformed = .{ .whole_program = new_program } };
}
// REPRO (pins the "top-level-only" transform-lowering class — see memory:
// nested-transform-lowering-gap): the SAME renderHTML transform above, invoked
// in CONTINUATION position (downstream of a pipeline binding) instead of at top
// level. The transform's matcher inspects flow.inv() — the flow ROOT — so a
// continuation-position invocation is NEVER matched, the comptime invocation is
// never replaced, and the pass runner raises a RAW HOST PANIC
// ("Invocation not replaced!" -> src/transform_pass_runner.zig:1036) instead of
// a koru-level diagnostic.
//
// TWO defects are pinned here: (1) the CAPABILITY gap — transforms don't compose
// in continuation position; (2) the raw HOST LEAK — a Zig panic with no
// koru-level diagnostic and no source location. First fix rung: replace the
// panic with a koru diagnostic naming the continuation-position constraint (this
// pin goes GREEN — the CONTAINS assertion is satisfied). Capability rung: make
// the transform actually compose in continuation position, then flip
// MUST_ERROR -> MUST_RUN with expected.txt.
~tor seed {} -> i64
~proc seed|zig {
return 1;
}
// The bind is spelled `_` because nothing reads it — `seed()` is here only to
// put `renderHTML` in continuation position, which is what this pin measures.
// A named bind would now be KORU100 (510_110) and would mask that.
~seed(): _ |> renderHTML { <div>Hello, World!</div> }
| rendered h |> std/io:print.ln(h.html)
Actual compiler output
error[KORU124]: transform 'renderHTML' invoked in continuation position is not supported here
--> tests/regression/200_COMPILER_FEATURES/210_PARSER/210_158_transform_continuation_position_panic/input.kz:248:0
this transform uses the whole-program escape, which matches flow-root invocations only; a continuation-position invocation is never rewritten (frontier: 210_024_source_scope_capture).
fix: invoke 'renderHTML' at top level, or have it return a site-local SiteResult instead of a whole_program.Compiler must reject:
Compilation must fail with a diagnostic.
Flows
flow ~seed click a branch to expand · @labels scroll to their anchor
seed
Test Configuration
MUST_ERROR