Fennel language preview

1. A function and a loop

fn, local, each, and Lua built-ins

horizon-dark

;; sum two numbers
(fn add [a b]
  (+ a b))

(local greeting :hello)
(each [i v (ipairs [1 2 3])]
  (print i v))

(print (add 1 2) greeting "done")

atom-one-dark

;; sum two numbers
(fn add [a b]
  (+ a b))

(local greeting :hello)
(each [i v (ipairs [1 2 3])]
  (print i v))

(print (add 1 2) greeting "done")

github-dark

;; sum two numbers
(fn add [a b]
  (+ a b))

(local greeting :hello)
(each [i v (ipairs [1 2 3])]
  (print i v))

(print (add 1 2) greeting "done")

dracula

;; sum two numbers
(fn add [a b]
  (+ a b))

(local greeting :hello)
(each [i v (ipairs [1 2 3])]
  (print i v))

(print (add 1 2) greeting "done")

nord

;; sum two numbers
(fn add [a b]
  (+ a b))

(local greeting :hello)
(each [i v (ipairs [1 2 3])]
  (print i v))

(print (add 1 2) greeting "done")

github

;; sum two numbers
(fn add [a b]
  (+ a b))

(local greeting :hello)
(each [i v (ipairs [1 2 3])]
  (print i v))

(print (add 1 2) greeting "done")

2. Tables and iteration

a table literal, keyword keys, and icollect

horizon-dark

(local person {:name "Ada" :age 30})

(icollect [_ v (pairs person)]
  (tostring v))

(print person.name)

atom-one-dark

(local person {:name "Ada" :age 30})

(icollect [_ v (pairs person)]
  (tostring v))

(print person.name)

github-dark

(local person {:name "Ada" :age 30})

(icollect [_ v (pairs person)]
  (tostring v))

(print person.name)

dracula

(local person {:name "Ada" :age 30})

(icollect [_ v (pairs person)]
  (tostring v))

(print person.name)

nord

(local person {:name "Ada" :age 30})

(icollect [_ v (pairs person)]
  (tostring v))

(print person.name)

github

(local person {:name "Ada" :age 30})

(icollect [_ v (pairs person)]
  (tostring v))

(print person.name)

3. Conditionals and match

when, match, and accumulate

horizon-dark

(fn classify [n]
  (match n
    0 :zero
    _ (if (> n 0) :positive :negative)))

(accumulate [total 0
             _ n (ipairs [1 2 3])]
  (+ total n))

atom-one-dark

(fn classify [n]
  (match n
    0 :zero
    _ (if (> n 0) :positive :negative)))

(accumulate [total 0
             _ n (ipairs [1 2 3])]
  (+ total n))

github-dark

(fn classify [n]
  (match n
    0 :zero
    _ (if (> n 0) :positive :negative)))

(accumulate [total 0
             _ n (ipairs [1 2 3])]
  (+ total n))

dracula

(fn classify [n]
  (match n
    0 :zero
    _ (if (> n 0) :positive :negative)))

(accumulate [total 0
             _ n (ipairs [1 2 3])]
  (+ total n))

nord

(fn classify [n]
  (match n
    0 :zero
    _ (if (> n 0) :positive :negative)))

(accumulate [total 0
             _ n (ipairs [1 2 3])]
  (+ total n))

github

(fn classify [n]
  (match n
    0 :zero
    _ (if (> n 0) :positive :negative)))

(accumulate [total 0
             _ n (ipairs [1 2 3])]
  (+ total n))