functions F.mapt2a and F.mapk2a

map functions on tables that return arrays

Author: Christophe Delord

doc/F.md

@@ -1011,6 +1011,22 @@ t:mapk(f)
 > maps `f` to the keys and values of `t` and returns
 > `{k1=f(k1, t[k1]), k2=f(k2, t[k2]), ...}`
 
+``` lua
+F.mapt2a(f, t)
+t:mapt2a(f)
+```
+
+> maps `f` to the values of `t` and returns the array
+> `{f(t[k1]), f(t[k2]), ...}`
+
+``` lua
+F.mapk2a(f, t)
+t:mapk2a(f)
+```
+
+> maps `f` to the keys and the values of `t` and returns the array
+> `{f(k1, t[k1]), f(k2, t[k2]), ...}`
+
 ``` lua
 F.reverse(xs)
 xs:reverse()

libluax/F/F.lua

@@ -2322,6 +2322,42 @@ register2 "mapk" (function(f, t)
     return setmetatable(t2, mt)
 end)
 
+--[[@@@
+```lua
+F.mapt2a(f, t)
+t:mapt2a(f)
+```
+> maps `f` to the values of `t` and returns the array `{f(t[k1]), f(t[k2]), ...}`
+@@@]]
+
+register2 "mapt2a" (function(f, t)
+    local ys = {}
+    local i = 0
+    for _, v in F_pairs(t) do
+        i = i+1
+        ys[i] = f(v)
+    end
+    return setmetatable(ys, mt)
+end)
+
+--[[@@@
+```lua
+F.mapk2a(f, t)
+t:mapk2a(f)
+```
+> maps `f` to the keys and the values of `t` and returns the array `{f(k1, t[k1]), f(k2, t[k2]), ...}`
+@@@]]
+
+register2 "mapk2a" (function(f, t)
+    local ys = {}
+    local i = 0
+    for k, v in F_pairs(t) do
+        i = i+1
+        ys[i] = f(k, v)
+    end
+    return setmetatable(ys, mt)
+end)
+
 --[[@@@
 ```lua
 F.reverse(xs)

tests/luax-tests/F_test.lua

@@ -980,6 +980,12 @@ local function table_transformations()
     eq(F.mapk(h, t), {x="x:20",y="y:40",z="z:60"})
     eq(t:mapk(h), {x="x:20",y="y:40",z="z:60"})
 
+    eq(F.mapt2a(f, t), {20,40,60})
+    eq(t:mapt2a(f), {20,40,60})
+
+    eq(F.mapk2a(h, t), {"x:20","y:40","z:60"})
+    eq(t:mapk2a(h), {"x:20","y:40","z:60"})
+
     eq(F.reverse(xs), {30,20,10})
     eq(xs:reverse(), {30,20,10})