1 files changed, 143 insertions, 0 deletions
diff --git a/src/luarocks/fun.lua b/src/luarocks/fun.lua
new file mode 100644
index 0000000..80bf7c2
--- /dev/null
+++ b/src/luarocks/fun.lua
@@ -0,0 +1,143 @@
+
+--- A set of basic functional utilities
+local fun = {}
+
+local unpack = table.unpack or unpack
+
+function fun.concat(xs, ys)
+   local rs = {}
+   local n = #xs
+   for i = 1, n do
+      rs[i] = xs[i]
+   end
+   for i = 1, #ys do
+      rs[i + n] = ys[i]
+   end
+   return rs
+end
+
+function fun.contains(xs, v)
+   for _, x in ipairs(xs) do
+      if v == x then
+         return true
+      end
+   end
+   return false
+end
+
+function fun.map(xs, f)
+   local rs = {}
+   for i = 1, #xs do
+      rs[i] = f(xs[i])
+   end
+   return rs
+end
+
+function fun.filter(xs, f)
+   local rs = {}
+   for i = 1, #xs do
+      local v = xs[i]
+      if f(v) then
+         rs[#rs+1] = v
+      end
+   end
+   return rs
+end
+
+function fun.traverse(t, f)
+   return fun.map(t, function(x)
+      return type(x) == "table" and fun.traverse(x, f) or f(x)
+   end)
+end
+
+function fun.reverse_in(t)
+   for i = 1, math.floor(#t/2) do
+      local m, n = i, #t - i + 1
+      local a, b = t[m], t[n]
+      t[m] = b
+      t[n] = a
+   end
+   return t
+end
+
+function fun.sort_in(t, f)
+   table.sort(t, f)
+   return t
+end
+
+function fun.flip(f)
+   return function(a, b)
+      return f(b, a)
+   end
+end
+
+function fun.find(xs, f)
+   if type(xs) == "function" then
+      for v in xs do
+         local x = f(v)
+         if x then
+            return x
+         end
+      end
+   elseif type(xs) == "table" then
+      for _, v in ipairs(xs) do
+         local x = f(v)
+         if x then
+            return x
+         end
+      end
+   end
+end
+
+function fun.partial(f, ...)
+   local n = select("#", ...)
+   if n == 1 then
+      local a = ...
+      return function(...)
+         return f(a, ...)
+      end
+   elseif n == 2 then
+      local a, b = ...
+      return function(...)
+         return f(a, b, ...)
+      end
+   else
+      local pargs = { n = n, ... }
+      return function(...)
+         local m = select("#", ...)
+         local fargs = { ... }
+         local args = {}
+         for i = 1, n do
+            args[i] = pargs[i]
+         end
+         for i = 1, m do
+            args[i+n] = fargs[i]
+         end
+         return f(unpack(args, 1, n+m))
+      end
+   end
+end
+
+function fun.memoize(fn)
+   local memory = setmetatable({}, { __mode = "k" })
+   local errors = setmetatable({}, { __mode = "k" })
+   local NIL = {}
+   return function(arg)
+      if memory[arg] then
+         if memory[arg] == NIL then
+            return nil, errors[arg]
+         end
+         return memory[arg]
+      end
+      local ret1, ret2 = fn(arg)
+      if ret1 ~= nil then
+         memory[arg] = ret1
+      else
+         memory[arg] = NIL
+         errors[arg] = ret2
+      end
+      return ret1, ret2
+   end
+end
+
+return fun