perf(mustache): Removed lambda support.

It really wasn't benefitting us in any way.

AGENTS.md

@@ -416,7 +416,6 @@ Spec-compliant implementation at `mustache/`. See `mustache/SPEC.md` for the imp
 | `diagnostic.odin` | Rust-style error formatter: `format_error` (multi-line context, ANSI colors via `core:terminal/ansi`, `colorize` param), `format_render_error` (formats `Error`), `line_col`, `line_text`, `context_extent`, `count_lines`, `digit_count`, `should_colorize`. |
 | `suggest.odin` | Strict-warning helpers: `validate_key_path` (walks dotted path, crosses maps silently), `suggest_correction` (Levenshtein via `core:strings/levenshtein_distance`), `collect_struct_keys` (via reflection, recurses into `using`), `struct_has_field` (distinguishes missing field from nil value — needed for `Maybe(bool)`), `collect_partial_names`, `collect_block_names`. |
 | `spec_test.odin` | JSON spec test runner — loads `spec/specs/*.json`, runs each test case. Uses `log.nil_logger()` to suppress expected warnings. |
-| `lambda_test.odin` | Spec lambda tests |
 | `pipes_test.odin` | Pipe filter tests (`group_by` + `format`) |
 | `diagnostic_test.odin` | Golden-output tests for `format_error` (multi-line context, edge cases, alignment, caret position, hint) + parser error message brace-escaping |
 | `suggest_test.odin` | Tests for `validate_key_path`, `suggest_correction`, `struct_has_field` with `Maybe(bool)` and `using`-promoted fields |
@@ -460,13 +459,6 @@ Rust-style error messages with multi-line source context, caret underlines, and
 
 **Block override source tracking**: `Block_Override.source: Template` ensures warnings inside block overrides point at the override's source file (e.g., `page.html`), not the parent template (`base.html`).
 
-### Lambdas
-
-Spec-compliant. Stored as `any` values in the data context.
-
-- **Interpolation lambdas**: `proc() -> string`, `proc() -> int`, `proc() -> bool` — called via `call_interp_lambda`, result stringified and escaped.
-- **Section lambdas**: `proc(string) -> string`, `proc(string) -> int`, `proc(string) -> bool` — called via `call_section_lambda` with the raw section text (`node.content`). String result is re-parsed as mustache and rendered against the current context stack.
-
 ### Pipes
 
 `{{key | op args…}}` for interpolation, `{{#key | op args…}}…{{/key}}` for sections. Stored as `[dynamic; MAX_PIPES]Pipe_Filter` on each `Node`. Applied in the renderer via `apply_pipeline` before truthiness/interpolation. Implemented filters:

TODOS.md

@@ -121,6 +121,9 @@
   - [ ] configure opt-out of automatic sections being added to menu.
   - [ ] nested menus (i.e. `parent` support)
 - [ ] get rid of the global variables in the `treesitter` package.
+- [ ] enforce heading structure.
+  - [ ] Either frontmatter.title set, or 1 h1 tag at top, not both
+  - [ ] No skipping. 
 - [ ] Consider using `or_else` when applying default values to structs. i.e.
 ```odin
 package main

mustache/data.odin

@@ -175,32 +175,6 @@ is_truthy :: proc(a: any) -> bool {
 	}
 }
 
-call_interp_lambda :: proc(val: any) -> (result: string, ok: bool) {
-	switch v in val {
-	case proc() -> string:
-		return v(), true
-	case proc() -> int:
-		return fmt.tprintf("%d", v()), true
-	case proc() -> bool:
-		return "true" if v() else "false", true
-	case:
-		return "", false
-	}
-}
-
-call_section_lambda :: proc(val: any, text: string) -> (result: string, ok: bool) {
-	switch v in val {
-	case proc(_: string) -> string:
-		return v(text), true
-	case proc(_: string) -> int:
-		return fmt.tprintf("%d", v(text)), true
-	case proc(_: string) -> bool:
-		return "true" if v(text) else "false", true
-	case:
-		return "", false
-	}
-}
-
 // list_info returns element type info, count, and data pointer for a list value.
 // Returns elem_info=nil if the value is not a list.
 list_info :: proc(a: any) -> (elem_info: ^runtime.Type_Info, count: int, data: rawptr) {

mustache/lambda_test.odin

@@ -1,154 +0,0 @@
-#+test
-package mustache
-
-import "core:fmt"
-import "core:testing"
-
-/*
-
-// --- Spec test 1: Interpolation ---
-// A lambda's return value should be interpolated.
-
-Interp_Data :: struct {
-	lambda: proc() -> string,
-	planet: string,
-}
-
-Interp_Data_Int :: struct {
-	lambda: proc() -> int,
-	planet: string,
-}
-
-@(test)
-test_lambda_interpolation :: proc(t: ^testing.T) {
-	data := Interp_Data {
-		lambda = proc() -> string {return "world"},
-	}
-	tpl, _ := parse("Hello, {{lambda}}!", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "Hello, world!")
-}
-
-// --- Spec test 2: Interpolation - Expansion ---
-// A lambda's return value should be parsed.
-
-@(test)
-test_lambda_interpolation_expansion :: proc(t: ^testing.T) {
-	data := Interp_Data {
-		lambda = proc() -> string {return "{{planet}}"},
-		planet = "world",
-	}
-	tpl, _ := parse("Hello, {{lambda}}!", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "Hello, world!")
-}
-
-// --- Spec test 4: Interpolation - Multiple Calls ---
-// Interpolated lambdas should not be cached.
-
-counter_lambda :: proc() -> int {
-	@(static) call_count := 0
-	call_count += 1
-	return call_count
-}
-
-@(test)
-test_lambda_interpolation_multiple_calls :: proc(t: ^testing.T) {
-	data := Interp_Data_Int {
-		lambda = counter_lambda,
-	}
-	tpl, _ := parse("{{lambda}} == {{{lambda}}} == {{lambda}}", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "1 == 2 == 3")
-}
-
-// --- Spec test 5: Escaping ---
-// Lambda results should be appropriately escaped.
-
-@(test)
-test_lambda_escaping :: proc(t: ^testing.T) {
-	data := Interp_Data {
-		lambda = proc() -> string {return ">"},
-	}
-	tpl, _ := parse("<{{lambda}}{{{lambda}}}", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "<&gt;>")
-}
-
-// --- Spec test 6: Section ---
-// Lambdas used for sections should receive the raw section string.
-
-Section_Data :: struct {
-	lambda: proc(_: string) -> string,
-	x:      string,
-	planet: string,
-}
-
-@(test)
-test_lambda_section :: proc(t: ^testing.T) {
-	data := Section_Data {
-		lambda = proc(text: string) -> string {
-			if text == "{{x}}" {return "yes"} else {return "no"}
-		},
-		x = "Error!",
-	}
-	tpl, _ := parse("<{{#lambda}}{{x}}{{/lambda}}>", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "<yes>")
-}
-
-// --- Spec test 7: Section - Expansion ---
-// Lambdas used for sections should have their results parsed.
-
-@(test)
-test_lambda_section_expansion :: proc(t: ^testing.T) {
-	data := Section_Data {
-		lambda = proc(text: string) -> string {
-			return fmt.tprintf("%s{{{{planet}}}}%s", text, text)
-		},
-		planet = "Earth",
-	}
-	tpl, _ := parse("<{{#lambda}}-{{/lambda}}>", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "<-Earth->")
-}
-
-// --- Spec test 9: Section - Multiple Calls ---
-// Lambdas used for sections should not be cached.
-
-@(test)
-test_lambda_section_multiple_calls :: proc(t: ^testing.T) {
-	data := Section_Data {
-		lambda = proc(text: string) -> string {
-			return fmt.tprintf("__%s__", text)
-		},
-	}
-	tpl, _ := parse(
-		"{{#lambda}}FILE{{/lambda}} != {{#lambda}}LINE{{/lambda}}",
-		"<test>",
-		context.temp_allocator,
-	)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "__FILE__ != __LINE__")
-}
-
-// --- Spec test 10: Inverted Section ---
-// Lambdas used for inverted sections should be considered truthy.
-
-Inverted_Data :: struct {
-	lambda: proc(_: string) -> bool,
-	static: string,
-}
-
-@(test)
-test_lambda_inverted_section :: proc(t: ^testing.T) {
-	data := Inverted_Data {
-		lambda = proc(text: string) -> bool {return false},
-		static = "static",
-	}
-	tpl, _ := parse("<{{^lambda}}{{static}}{{/lambda}}>", "<test>", context.temp_allocator)
-	result, _ := render(tpl, data, {}, context.temp_allocator)
-	testing.expect_value(t, result, "<>")
-}
-
-*/

mustache/mustache.odin

@@ -625,30 +625,7 @@ render_nodes :: proc(
 				}
 				val = transformed
 			}
-			if result_str, ok := call_interp_lambda(val); ok {
-				sub_tpl, perr := parse(
-					result_str,
-					fmt.tprintf("<lambda output from '%s'>", node.key),
-					context.temp_allocator,
-					context.temp_allocator,
-				)
-				if perr == nil {
-					temp: strings.Builder
-					strings.builder_init(&temp, context.temp_allocator)
-					render_nodes(
-						sub_tpl,
-						sub_tpl.nodes[:],
-						ctx,
-						partials,
-						&temp,
-						blocks,
-						nil,
-					) or_return
-					write_value(b, strings.to_string(temp), escape = true)
-				}
-			} else {
 			write_value(b, val, escape = true)
-			}
 			i += 1
 
 		case .Unescaped:
@@ -667,30 +644,7 @@ render_nodes :: proc(
 				}
 				val = transformed
 			}
-			if result_str, ok := call_interp_lambda(val); ok {
-				sub_tpl, perr := parse(
-					result_str,
-					fmt.tprintf("<lambda output from '%s'>", node.key),
-					context.temp_allocator,
-					context.temp_allocator,
-				)
-				if perr == nil {
-					temp: strings.Builder
-					strings.builder_init(&temp, context.temp_allocator)
-					render_nodes(
-						sub_tpl,
-						sub_tpl.nodes[:],
-						ctx,
-						partials,
-						&temp,
-						blocks,
-						nil,
-					) or_return
-					write_value(b, strings.to_string(temp), escape = false)
-				}
-			} else {
 			write_value(b, val, escape = false)
-			}
 			i += 1
 
 		case .Section:
@@ -705,25 +659,7 @@ render_nodes :: proc(
 				}
 				val = transformed
 			}
-			if result_str, ok := call_section_lambda(val, node.content); ok {
+			if is_truthy(val) {
-				sub_tpl, perr := parse(
-					result_str,
-					fmt.tprintf("<lambda output from '%s'>", node.key),
-					context.temp_allocator,
-					context.temp_allocator,
-				)
-				if perr == nil {
-					render_nodes(
-						sub_tpl,
-						sub_tpl.nodes[:],
-						ctx,
-						partials,
-						b,
-						blocks,
-						nil,
-					) or_return
-				}
-			} else if is_truthy(val) {
 				children := node.children
 				elem_info, count, data := list_info(val)
 				if elem_info != nil {