The Frankie Language

# &. — nil-safe navigation operator
user    = {name: "Alice", age: 30}
missing = nil
puts user["name"]&.upcase      # ALICE
puts missing&.upcase           # nil
puts missing&.upcase&.reverse  # nil
def greet(name)
  display = name&.upcase
  if display == nil
    puts "Hello, stranger!"
  else
    puts "Hello, #{display}!"
  end
end
greet("bob")  # Hello, BOB!
greet(nil)   # Hello, stranger!

# R-style stats + pipe operator
data = [23, 45, 12, 67, 34, 89]
puts mean(data)    # 45.0
puts stdev(data)   # 27.9
puts median(data)  # 39.5
data |> sum |> puts  # 270
top3 = data.sort_by do |x| -x end.take(3)
puts top3  # [89, 67, 45]
# Iterators
words = ["banana", "fig", "cherry"]
long = words.select do |w| w.length > 4 end
puts long  # [banana, cherry]
[1,2,3,4,5,6].each do |n|
  next if n % 2 == 0
  break if n > 5
  puts n  # 1 3 5
end

# Lambdas — first-class functions
double = ->(x) { x * 2 }
add    = ->(a, b) { a + b }
puts double.call(7)      # 14
puts add.call(3, 4)      # 7
def apply(fn, val)
  return fn.call(val)
end
puts apply(double, 9)    # 18
# Hash merge | and group_by
cfg = {color: "blue"} | {color: "red", size: "md"}
puts cfg["color"]        # red
nums = [1,2,3,4,5,6]
by_p = nums.group_by do |n|
  n % 2 == 0 ? "even" : "odd"
end
puts by_p["even"]        # [2, 4, 6]
[1,2,3,4].each_slice(2) do |s| puts s end

# record — lightweight named data objects
record Point(x, y)
record Employee(name, dept, salary)
p1  = Point(3, 4)
emp = Employee("Alice", "Eng", 95000)
puts p1           # Point(x: 3, y: 4)
puts emp["dept"]   # Eng
# dig — safe nested access
cfg = {db: {host: "localhost", port: 5432}}
puts cfg.dig("db", "host")    # localhost
puts cfg.dig("db", "missing") # nil
# zip() standalone + .env auto-load
zip(["a","b"], [1,2]).each do |p|
  puts "#{p[0]}:#{p[1]}"
end
# frankiec fmt / docs / readline REPL
db = env("DB_PATH", "app.db")
puts db

# Ternary operator
grade = score >= 90 ? "A" : score >= 70 ? "B" : "C"

# Keyword default parameters
def connect(host, port: 5432, ssl: true)
  puts "#{host}:#{port} ssl=#{ssl}"
end

# Splat multi-assign
first, *mid, last = [1, 2, 3, 4, 5]

# const keyword
const MAX = 100

# Lambda call syntax everywhere
double = ->(x) { x * 2 }
puts double.(6)

# frankieauth stitch
stitch "frankieauth"
app.use do |req, next_fn|
  if not basic_auth_ok?(req, "admin", env("PASS"))
    halt(401, "Unauthorized")
  end
  next_fn.(req)
end

# frankiec check — CI lint
# $ frankiec check app.fk   → exit 0 or 1
# frankiec new myapp        → full scaffold

# Hash destructuring
user = {name: "Alice", role: "admin", age: 30}
{name, role} = user
puts "#{name} is a #{role}"

# Shape pattern matching
case user
when {role: "admin"}
  puts green("Admin access granted")
when {role: "moderator"}
  puts yellow("Moderator tools")
end

# Mustache templates
stitch "frankietemplate"
html = render_file("./views/index.html", {title: "Home", user: user})

# spawn — fire and forget
spawn do
  send_welcome_email(user["email"])
end

# Middleware
app.use do |req, next_fn|
  puts "→ #{req.method} #{req.path}"
  next_fn.(req)
end

# frankiestring v2 — clean string helpers
stitch "frankiestring"
puts pad_left("42", 6, "0")              # "000042"
puts slugify("Hello World!")           # "hello-world"
puts word_wrap("The quick brown fox", 12)

# .sum do — projected sum in one step
cart = [{price: 0.99, qty: 4}, {price: 2.49, qty: 2}]
total = cart.sum do |item|
  item["price"] * item["qty"]
end
puts total   # 8.94

# assert_approx_eq — float testing
assert_approx_eq(sqrt(2.0), 1.4142, 0.0001, "sqrt(2)")
run_tests()

# Cookie-backed session — no server state
s = session(req, resp)
s["count"] = (s["count"] or 0) + 1
s.save()

# stitch — drop a .fk file in ./stitches/ and load it by name
stitch "frankieforms"
stitch "frankietable"
stitch "frankiecolor"

# Form validation
rules = {email: [{rule: "required"}, {rule: "email"}]}
puts valid?({email: "[email protected]"}, rules)  # true

# ASCII tables
rows = [{name: "Alice", score: 95}, {name: "Bob", score: 87}]
puts table(rows)

# Terminal colors
puts red("Error!")
puts green("Done!")
puts success("All tests passed")

# ? in function names — now works
def even?(n)
  n % 2 == 0
end
puts even?(4)   # true

# .gsub with block — transform each match
puts "hello world".gsub(/[aeiou]/) do |m| m.upcase end
# hEllO wOrld

# .map_hash — transform a hash into a new hash
prices = {apple: 1.20, banana: 0.50}
puts prices.map_hash do |k, v| [k, v * 2] end

# round(x, n) — finally
puts round(3.14159, 2)   # 3.14

# .product — cartesian product
puts [1,2].product([3,4])   # [[1,3],[1,4],[2,3],[2,4]]

# rescue FileNotFoundError now actually works
begin
  file_read("missing.txt")
rescue FileNotFoundError e
  puts "Caught: #{e}"
end

# frankiec watch main.fk   ← re-run on save
# frankiec repl --no-banner ← headless REPL

# Implicit return — no 'return' needed
def double(x)
  x * 2
end
puts double(7)   # 14

# Inline if expression
grade = if score >= 90 then "A" else "B" end

# String .replace() and .format(hash)
puts "hello world".replace("world", "Frankie")
puts "Hi, {name}!".format({name: "Alice"})

# .zip_with — pair-wise transform
puts [1,2,3].zip_with([10,20,30]) do |a, b|
  a + b
end   # [11, 22, 33]

# Multiple return values
def minmax(v)
  [min(v), max(v)]
end
lo, hi = minmax([3,1,4,1,5,9])

# String & vector * repetition
puts "ha" * 3           # hahaha
puts [0] * 5            # [0, 0, 0, 0, 0]
# Heredoc <<~ strips indent + interpolates
v = "1.10"
sql = <<~SQL
  SELECT * FROM users
  WHERE version = '#{v}'
SQL
puts sql
# times() standalone + map_with_index
times(3) do |i| puts "tick #{i}" end
puts ["a","b","c"].map_with_index do |v, i|
  "#{i}:#{v}"
end
# pp + encode/decode
pp({host: "localhost", port: 3000})
puts "hi".encode  # [104, 105]

## Distance between two points.
## @param p1  A Point record
## @param p2  A Point record
## @return    Float distance
def distance(p1, p2)
  dx = p1["x"] - p2["x"]
  dy = p1["y"] - p2["y"]
  return sqrt(dx*dx + dy*dy)
end
# frankiec docs generates Markdown
# frankiec fmt --write myfile.fk
# frankiec fmt --check  (CI mode)
# frankiec --help / frankiec run --help
# Named rescue without variable:
begin
  x = 1 // 0
rescue ZeroDivisionError
  puts "caught"
end