mirrors/janet
1
0
Fork 0
mirror of https://github.com/janet-lang/janet synced 2024-12-25 07:50:27 +00:00
Code Issues 1 Releases Wiki Activity

Fix typos and improve if/when-let macros

Browse Source 
In clojure when-let and if-let accept at most two forms and must both be true for the evaluatioh to take place. The implementation here does the same but can bind more forms
This commit is contained in:
Heefoo 2018-03-21 05:59:03 +02:00
parent c7de277f55
commit f3825caefa
1 changed files with 20 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
examples/utils.dst
View File

@ -1,4 +1,6 @@
(defn- reverse-array [t]
(defn- reverse-array
"Reverses the order of the elements in a given array"
[t]
(var n (dec (length t)) )
(var reversed [])
(while (>= n 0)
@ -7,7 +9,9 @@
reversed)
(defn- reverse-tuple [t]
(defn- reverse-tuple
"Reverses the order of the elements of a given tuple"
[t]
(def max (length t))
(var n 0)
(var reversed (tuple))
@ -33,30 +37,38 @@
exp-2))
(defmacro when-not
"Sorthand for (if (not ... "
"Sorthand for (when (not ... "
[condition exp-1]
(tuple 'when (tuple 'not condition) exp-1))
(defmacro if-let
"Takes the first one or two forms in vector and if true binds
all the forms with let and evaluates first expression else
evaluates the second"
[bindings then else]
(def head (ast-unwrap1 bindings))
(tuple 'let head
(tuple 'if (get head 1)
(tuple 'if (and (get head 1) (if (get head 2) (get head 3) true))
then
else)))
(defmacro when-let
[bindings & then]
"Takes the first one or two forms in vector and if true binds
all the forms with let and evaluates body "
[bindings & body]
(def head (ast-unwrap1 bindings))
(tuple 'let head
(tuple
'when
(get head 1) (apply tuple (array-concat ['do] (ast-unwrap1 then))) )))
(and (get head 1) (if (get head 2) (get head 3) true))
(apply tuple (array-concat ['do] (ast-unwrap1 body))) )))
(defn comp0-
(defn- comp0
"Compose two functions. Second function must accept only one argument)"
[f g] (fn [x] (f (g x))))
@ -77,6 +89,6 @@
(do
(def f (get functions 0))
(def g (get functions 1))
(apply comp (comp0- f g) (array-slice functions 2 -1))) )))
(apply comp (comp0 f g) (array-slice functions 2 -1))) )))