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What's New — Per Version

Each version of Frankie ships a runnable whats_new_vX.fk example file that demonstrates every new feature introduced in that release. Run any of them with:

frankiec run examples/whats_new_v118.fk

v1.18 — whats_new_v118.fk

Theme: "From projects to products" — edit (LSP), ship (bundle), connect (WebSockets), debug (breakpoint). Pure Python stdlib underneath, zero external dependencies, as always.

Feature Summary
frankiec lsp Language Server over stdio — live diagnostics, completion, hover docs in VS Code, Neovim, Helix, Zed
frankiec bundle Compile a program + all require/import/stitch targets into ONE self-contained .py — runs anywhere with Python 3.8+
WebSockets app.websocket("/ws/:room") do \|ws\| ... end server + ws_connect(url) client — hand-rolled RFC 6455
breakpoint Pause into a scoped debug REPL — vars, where, any Frankie expression; skipped when stdin isn't a tty
enum Status(pending, active, done) Named symbolic values — Status.pending, .values, .include?, case/when matching
benchmark "label" do ... end Time a block — prints ⏱ label: 12.3ms, returns elapsed ms
Set operations .union / .intersect / .difference — order-preserving, deduplicating
Numeric literals Underscores 1_250_000 + scientific notation 6.022e23
Project-wide tooling frankiec check . and frankiec fmt --write . recurse into directories
Stitch lockfile stitch.lock with sha256 pins — frankiec stitch verify / update

v1.17 — whats_new_v117.fk

Theme: "Programs that grow" — namespacing, real static checking, typed errors, first-class ranges, easy concurrency, TCP sockets, and a stitch installer. Everything still pure Python stdlib, zero dependencies.

Feature Summary
import "path" as name Load a .fk file into its own namespace — geo.circle_area(5), geo.PI; modules cached; require unchanged
error TypeName User-defined error types — raise ValidationError, "msg", caught with rescue ValidationError => e
rescue Type => e New Ruby-style rescue binding (old rescue Type e form still works)
First-class ranges r = 1..10 prints as 1..10; .to_vec, .include?, .step(n), .sum, .first, .last
Range case/when when 90..100 tests membership — works with range values in variables too
Record dot access p1.x instead of p1["x"] — hash-style access still works
parallel_map parallel_map(urls, workers: 8) do \|u\| ... end — thread-pool map, results in input order
TCP sockets tcp_connect / tcp_listen / tcp_serve — send_line, recv_line, peer, threaded server loop
frankiec check Real static analysis — undefined names, wrong arg counts, unused locals; --strict for CI
Cross-file tracebacks Runtime errors point at the right file and line, in requires, imports and stitches
test groups test "name", tags: ["slow"] do ... end — filter with --filter / --tag
stub / unstub Swap any global function during tests — stub("shell", ->(cmd) { fake })
Stitch installer frankiec stitch install frankiecolor [--global], frankiec stitch list
REPL upgrades Bare expressions echo => value, _ holds last result, help <function> shows docs

v1.16.2 — whats_new_v116.fk

Theme: System Integration & Scripting Power — shell commands, environment loading, infinite loops, nil-coalescing assign, richer hash and string tools, and three new stitches for email, CLI parsing, and caching.

Feature Summary
shell(cmd) Run an OS command — returns {stdout, stderr, exit_code, ok}
dotenv(path) Load a .env file into the process environment — returns hash of loaded vars
loop do...end Infinite loop, exits only via break — cleaner than while true
\|\|= Nil-coalescing assign — config \|\|= load_defaults()
Hash#transform_values New hash with same keys, block-transformed values
Hash#transform_keys New hash with block-transformed keys, same values
Hash#deep_merge Recursive nested hash merge — unlike shallow .merge / \|
String#scan Extract all regex matches as a vector
frankiemail stitch Send email via SMTP — plain text, HTML, CC/BCC — zero deps
frankiecli stitch CLI argument parsing — flags, options, subcommands — zero deps
frankiecache stitch In-memory TTL cache — set/get/delete/clear/size — zero deps

v1.15 — whats_new_v115.fk

Theme: Language Polish & Developer Ergonomics — cleaner syntax, more powerful stdlib, and two new web stitches.

Feature Summary
Ternary operator x > 0 ? "pos" : "neg" — right-associative, valid in any expression position
Keyword default params def connect(host, port: 5432, ssl: true) — : syntax now accepted alongside =
Splat in multi-assign a, *rest = [1,2,3] and first, *mid, last = arr — capture remaining elements
const keyword Explicit constant declaration — reassignment warns and preserves original value
fn.(args) everywhere Lambda call syntax now works in all contexts, not just web middleware
json_encode Preferred name for json_dump; accepts pretty: true
hmac_sign / hmac_verify Promoted from internal _fk_* to public stdlib — signed tokens and webhook verification
base64_encode / base64_decode Standard Base64 encode/decode — useful for HTTP Basic Auth headers
String#format Named placeholder substitution: "Hello, {name}!".format({name: "Alice"})
.chars / .bytes Unicode-aware character vector and byte values from a string
Path helpers path_join, path_dirname, path_basename, path_extname, path_stem, path_absolute
Date arithmetic Date objects support + / - (days) and comparison operators
zip_with block a.zip_with(b) do \|x, y\| x + y end — element-wise combination
assert_not_nil / assert_in New test assertions for nil checks and membership
req.query_int/float/bool Typed query parameter helpers with defaults
frankieauth stitch HTTP Basic Auth + Bearer token auth — zero dependencies
frankieratelimit stitch Per-IP sliding-window rate limiting — zero dependencies
frankiec check Parse without executing — useful in CI
frankiec new Scaffold a complete project layout
frankiec watch Official file watcher — re-run on save

v1.14 — whats_new_v114.fk

Theme: Frankie for real web apps — concurrency, templates, signed cookies, middleware, static files, and two language upgrades that make working with data cleaner everywhere.

Feature Summary
spawn { } Run a block in a background thread — response goes out immediately, work continues behind the scenes
timeout(n) { } Kill a block that exceeds n seconds — raises TimeoutError, wrap in begin/rescue for graceful fallback
Async routes app.get_async / app.post_async etc. — non-blocking handlers, use await inside for slow I/O
Middleware stack app.use do |req, next_fn| — chain auth, logging, and rate-limiting; call next_fn.(req) to continue or return early to short-circuit
Static file serving app.static("./public") — serve a directory at /; app.static("./assets", "/static") for a URL prefix
frankietemplate Mustache-compatible template stitch — {{ var }}, {{{ raw }}}, {{# section }}, {{^ inverted }}, {{> partial }}, {{! comment }}
frankiecookie HMAC-signed cookies via Python's hmac stdlib — set_signed_cookie / get_signed_cookie returns nil if tampered
Hash destructuring {name, age} = user — pull symbol keys directly into variables; missing keys become nil
Shape pattern matching case user when {role: "admin"} — when now accepts hash literals, matches on subset of keysfrankiec new scaffold
Global stitch install install.py now correctly copies all stitches to ~/.frankie/stitches/ and lists each file installed
page_links docs Full web pagination example added — paginate + page_slice + page_links + frankietemplate working together

v1.13.1 — whats_new_v1131.fk

Theme: Gap closers — no new syntax, everything real programs needed and didn't have.

Feature Summary
frankiestring v2 Rewritten stitch: pad_left, pad_right, truncate, slugify, word_wrap, indent_lines — replaces clunky lfill/rfill API
Vector .sum do \|x\| Block form now works — projected sum without a two-step .map + sum
Vector .flat_map do \|x\| Multi-line block bodies now parse correctly
assert_approx_eq(a, b, delta, msg) Float comparison in tests with configurable delta (default 0.001)
run_tests() Now a public stdlib function — callable from any .fk file, not just frankiec test
session(req, resp) Cookie-backed session hash — read, mutate, .save(). Zero server state, single JSON cookie _fk_session
frankiec fmt blank lines Intentional blank lines between statement groups inside function bodies now preserved
frankiec fmt multi-line threshold Hashes/vectors whose inline form exceeds 60 chars auto-expand to one element per line
frankiec fmt idempotency Running fmt --write twice now produces identical output — safe for pre-commit hooks and CI
Heredoc in do...end blocks Fixed lexer bug — heredocs now work anywhere a string expression is valid
Hash.each do \|k, v\| Two-parameter block iteration confirmed and end-to-end tested
Symbol key round-trip in fmt {host: "x"} no longer becomes {"host": "x"} after formatting

v1.13 — whats_new_v113.fk

Theme: Stitches — a zero-dependency, zero-registry package system.

Feature Summary
stitch "name" keyword Load a package by name — resolves from ./stitches/ then ~/.frankie/stitches/
frankieforms Form field validation — required, min_length, max_length, email, numeric, alpha, matches_pattern
frankietable ASCII table rendering from a vector of hashes — table(rows) / table(rows, cols)
frankiecolor ANSI color helpers — red, green, yellow, bold, success, error, warn, info, colorize, strip_color
frankiepager Pagination math — paginate(opts), page_slice(items, page, per_page), page_links(pager, url_template)
frankieconfig Layered config loading: defaults → JSON file → env vars → overrides, with type coercion
frankiestring String utilities stitch (v1, superseded by v2 in v1.13.1)
? in function names def even?(n) now works — ? compiled transparently to _q in generated Python

v1.12 — whats_new_v112.fk

Theme: Filling stdlib gaps, fixing error handling, tooling polish.

Feature Summary
String .gsub with block Transform each regex match via a block — "hello".gsub("[aeiou]") do \|m\| m.upcase end
Hash .map_hash Transform a hash into a new hash — block returns [new_key, new_value]
round(x, n) Round to n decimal places — round(3.14159, 2) → 3.14
Vector .product(other) Cartesian product — [1,2].product([3,4]) → [[1,3],[1,4],[2,3],[2,4]]
String .chars Promoted to first-class documented method — chains into iterators
each_with_object + Hash Hash accumulator now explicitly documented and tested
assert_match / assert_nil Two new test runner assertions
rescue FileNotFoundError file_read and file_lines now raise the correct type
frankiec watch Re-run on save — frankiec watch main.fk
frankiec repl --no-banner Headless REPL for scripts and pipes
Friendlier runtime errors Type errors now say "Integer and String", not Python internals

v1.11 — whats_new_v111.fk (in docs/13_v111_features.md)

Theme: Ergonomics — removing paper cuts, making the common case obvious.

Feature Summary
Implicit return Last expression in a function is returned automatically
Inline if expression grade = if score >= 90 then "A" else "B" end
String .replace(old, new) The method new users always reach for first
String .format(hash) "Hello, {name}!".format({name: "Alice"})
.zip_with do \|a, b\| Pair-wise transform two vectors in one pass
Multiple return values lo, hi = min_max(data) — destructuring from functions
frankiec check boxed errors Parse errors now use the same box as runtime errors
REPL multi-line history ↑ recalls a full def...end block
frankiec fmt heredoc support Heredoc bodies preserved verbatim during formatting
String .delete(chars) "hello".delete("l") → "heo" — documented

v1.10 — whats_new_v110.fk

Theme: Expressiveness — more ways to write less.

Feature Summary
String * n / Vector * n "ha" * 3 → "hahaha" · [0] * 5 → [0,0,0,0,0]
Heredoc <<~TEXT Multi-line strings with auto indent-stripping and interpolation
times() standalone times(5) do \|i\| alongside 5.times do
flatten(depth) Flatten exactly n levels — flatten(1) vs deep flatten
map_with_index v.map_with_index do \|x, i\|
pp — pretty print pp({host: "localhost", port: 3000})
encode / decode "hi".encode → [104, 105] · [104, 105].decode → "hi"
Exit codes exit(0) / exit(1) — propagated to shell
--help flag frankiec run --help etc.

v1.9 — whats_new_v19.fk

Theme: Safety and tooling.

Feature Summary
Hash .dig config.dig("db", "host") — safe nested access, returns nil
zip() standalone zip([1,2,3], ["a","b","c"]) → [[1,"a"],[2,"b"],[3,"c"]]
Record types record Point(x, y) — named data objects built on Hash
frankiec fmt AST-based auto-formatter with --write and --check
frankiec docs Extract ## doc-comments to Markdown
REPL readline + history Arrow keys, Ctrl+R, tab completion, persistent ~/.frankie_history
.env auto-loading .env in the project root is loaded automatically at startup

v1.8 — whats_new_v18.fk

Theme: Functional programming and collection power.

Feature Summary
Lambdas ->(x) { x * 2 } — storable, passable first-class functions
Hash merge \| h1 \| h2 — right wins on conflict, chains naturally
group_by Bucket elements into a hash of arrays by block result
each_slice(n) Iterate in non-overlapping chunks
each_cons(n) Iterate with a sliding window

v1.7 — whats_new_v17.fk

Theme: Safety and real-world utility.

Feature Summary
Nil safety &. name&.upcase returns nil instead of crashing
template(str, hash) {{key}} placeholder substitution
File system ops file_mkdir, dir_exists, dir_list, file_copy, file_rename
assert_raises_typed Test that a specific error type is raised

v1.6 — whats_new_v16.fk

Theme: Control flow completeness.

Feature Summary
Compound assignment +=, -=, *=, /=, //=, **=, %=
Typed rescue rescue ZeroDivisionError e — catch specific error types
.find / .detect First element matching a block condition
frankiec test Built-in test runner

v1.5 — whats_new_v15.fk

Theme: Loop control, randomness, and collection utilities.

Feature Summary
next Skip to next iteration — like continue
break Exit a loop early
break value Exit with a result — result = loop.break n * 10
Constants UPPER_CASE — warn on reassignment
rand_int, rand_float Random number functions
shuffle, sample Random collection operations
sleep(n) Pause execution
sort_by Sort by computed key
min_by, max_by, sum_by Aggregate by key
unzip Split vector of pairs into two vectors

v1.4 — whats_new_v14.fk

Theme: Built-in web server.

Feature Summary
Web server web_app() — Sinatra-style routing
Route definitions .get, .post, .put, .delete, .patch
Path parameters /users/:id → req.params["id"]
Query parameters req.query["page"]
JSON body req.json — auto-parsed
Before/after filters app.before do, app.after do
Response helpers html_response, json_response, redirect, halt

v1.3 — whats_new_v13.fk

Theme: External data and project structure.

Feature Summary
JSON json_read, json_write, json_parse, json_dump
CSV csv_read, csv_write, csv_parse, csv_dump
DateTime now(), today(), date_parse(), date_from()
HTTP client http_get, http_post, http_put, http_delete
frankiec new Project scaffolding

v1.2 (no whats_new file)

Theme: Database and multi-file programs.

Feature Summary
SQLite built-in db_open, db.query, db.insert, db.exec, transactions
require Load other .fk files — each loaded at most once

v1.1 — whats_new_v11.fk

Theme: Collection power.

Feature Summary
select / reject Filter a vector by a condition
reduce / inject Fold a vector into a single value
any? / all? / none? Boolean tests across a collection
each_with_object Iterate with a shared accumulator
take, drop, chunk, tally, compact Collection utilities
flat_map, zip Flattening and pairing
case / when Pattern matching on values
Destructuring assignment a, b, c = [1, 2, 3]
New string methods .chomp, .chop, .center, .ljust, .rjust, .squeeze, .tr
count with block Count elements matching a condition

v1.0 (initial release)

The foundation: variables, strings with #{} interpolation, integers, floats, booleans, nil, vectors, hashes, if/elsif/else/unless, while/until/for, functions with default params, begin/rescue/ensure, raise, regex (matches, match_all, sub, gsub, =~), file I/O (file_read, file_write), R-style statistics (mean, stdev, median, sum), vectorised arithmetic, the pipe operator |>, seq, linspace, the REPL, and frankiec run/build/check.