diff options
| -rw-r--r-- | .dir-locals.el | 4 | ||||
| -rw-r--r-- | README.org | 40 | ||||
| -rw-r--r-- | fn.fnl | 42 | ||||
| -rw-r--r-- | macros/fn.fnl | 84 |
4 files changed, 128 insertions, 42 deletions
diff --git a/.dir-locals.el b/.dir-locals.el new file mode 100644 index 0000000..3c181f6 --- /dev/null +++ b/.dir-locals.el @@ -0,0 +1,4 @@ +;;; Directory Local Variables +;;; For more information see (info "(emacs) Directory Variables") + +((fennel-mode . ((eval . (put 'fn* 'fennel-indent-function 'defun))))) @@ -1,3 +1,4 @@ + * Fennel Cljlib Library for [[https://fennel-lang.org/][Fennel]] language that adds a lot of functions from [[https://clojure.org/][Clojure]] standard library. This is not a one to one port of Clojure =core=, because many Clojure functions require certain guarantees, like immutability of the underlying data structures. @@ -9,6 +10,45 @@ Goals of this project are: - Be close to the platform, e.g. implement functions in a way that is efficient to use in Lua VM, - Be well documented library, with good test coverage. +** Macros +*** =fn*= +Clojure's =defn= equivalent. +Returns a function of fixed arity by doing runtime dispatch, based on argument amount. +Capable of producing multi-arity functions: + +#+begin_src fennel + (fn* square "square number" [x] (^ x 2)) + + (square 9) ;; 81 + (square 1 2) ;; error + + (fn* range + "Returns increasing sequence of numbers from `lower' to `upper'. + If `lower' is not provided, sequence starts from zero. + Accepts optional `step'" + ([upper] (range 0 upper 1)) + ([lower upper] (range lower upper 1)) + ([lower upper step] + (let [res []] + (for [i lower upper step] + (table.insert res i)) + res))) + + (range 10) + ;; [0 1 2 3 4 5 6 7 8 9 10] + (range -10 0) + ;; [-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0] + (range 0 1 0.2) + ;; [0.0 0.2 0.4 0.6 0.8 1.0] + + ;; both variants support up to one arity with & more: + (fn* list [& xs] xs) + + (list 1 2 3) + ;; [1 2 3] +#+end_src + +See =core.fnl= for more examples. ** Functions Here are some important functions from the library. Full set can be examined by requiring the module. @@ -1,42 +0,0 @@ -(fn string? [x] - (= (type x) "string")) - -(fn has-amp? [args] - (var res false) - (each [_ s (ipairs args)] - (when (= (tostring s) "&") - (set res true))) - res) - -(fn gen-arity [[args & body]] - (assert-compile (sequence? args) "fn* expects vector as it's parameter list. -Try wrapping arguments in square brackets." args) - (let [arg-length (if (has-amp? args) (sym "_") (length args)) - body (list 'let [args [(sym "...")]] (unpack body))] - (list arg-length body))) - -(fn fn* [name doc? ...] - (assert-compile (not (string? name)) "fn* expects symbol as function name" name) - (let [docstring (if (string? doc?) doc? nil) - args (if (sym? name) - (if (string? doc?) [...] [doc? ...]) - [name doc? ...]) - [x & xs] args] - (if (sequence? x) - ;; Ordinary function - (let [[args & body] args] - (if (sym? name) - `(fn ,name ,args ,docstring ,(unpack body)) - `(fn ,args ,docstring ,(unpack body)))) - ;; Multi-arity function - (list? x) - (let [bodies []] - (each [_ arity (ipairs args)] - (let [[arity body] (gen-arity arity)] - (table.insert bodies arity) - (table.insert bodies body))) - `(fn ,name [...] ,docstring (match (length [...]) ,(unpack bodies))))))) - -{: fn*} - -;; (import-macros {: fn*} :fn) (macrodebug (fn* f ([a] a))) diff --git a/macros/fn.fnl b/macros/fn.fnl new file mode 100644 index 0000000..5be8abe --- /dev/null +++ b/macros/fn.fnl @@ -0,0 +1,84 @@ +(local _unpack (or table.unpack unpack)) + +(fn string? [x] + (= (type x) "string")) + +(fn has-amp? [args] + (var res false) + (each [i s (ipairs args)] + (when (= (tostring s) "&") + (set res i))) + res) + +(fn gen-arity [[args & body]] + (assert-compile (sequence? args) "fn* expects vector as it's parameter list. +Try wrapping arguments in square brackets." args) + (list (length args) + (list 'let [args ['...]] (_unpack body)) + (has-amp? args))) + +(fn arity-dispatcher [size fixed amp-body name] + (let [bodies []] + (each [i body (pairs (doto fixed))] + (table.insert bodies (list '= size i)) + (table.insert bodies body)) + (when amp-body + (let [[i body] amp-body] + (table.insert bodies (list '>= size (- i 1))) + (table.insert bodies body))) + (table.insert + bodies + (list 'error + (.. "wrong argument amount" + (if name (.. " for " name) "")) 3)) + (list 'if (_unpack bodies)))) + + +(fn fn* [name doc? ...] + (assert-compile (not (string? name)) "fn* expects symbol as function name" name) + (let [docstring (if (string? doc?) doc? nil) + fname (if (sym? name) (tostring name)) + args (if (sym? name) + (if (string? doc?) [...] [doc? ...]) + [name doc? ...]) + [x] args + body (if (sequence? x) + ;; Single-arity function + (let [[args & body] args + [arity body amp] (gen-arity [args (_unpack body)])] + `(let [len# (length [...])] + ,(arity-dispatcher + 'len# + (if amp {} {arity body}) + (if amp [amp body]) + fname))) + ;; Multi-arity function + (list? x) + (let [bodies {} + amp-bodies {}] + (each [_ arity (ipairs args)] + (let [[n body amp] (gen-arity arity)] + (if amp + (do (table.insert amp-bodies amp) + (table.insert amp-bodies body) + (table.insert amp-bodies arity)) + (tset bodies n body)))) + (assert-compile (<= (length amp-bodies) 3) + "fn* must have only one arity with &:" + (. amp-bodies (length amp-bodies))) + `(let [len# (length [...])] + ,(arity-dispatcher + 'len# + bodies + (if (~= (next amp-bodies) nil) + amp-bodies) + fname))) + (assert-compile false "fn* expects vector as its arguments" x))] + (if (sym? name) + `(fn ,name [...] ,docstring ,body) + `(fn [...] ,docstring ,body)))) + +{: fn*} + +;; (import-macros {: fn*} :fn) +;; (fn* f ([a] a) ([a b] (+ a b))) |