From 0aae46ecc38005236210f7e243f02cac39ab1dc3 Mon Sep 17 00:00:00 2001
From: Alexander Pickering <alex@cogarr.net>
Date: Sun, 27 Jan 2019 10:32:09 -0500
Subject: Inital commit

---
 client/data/fn.lua | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 client/data/fn.lua

(limited to 'client/data/fn.lua')

diff --git a/client/data/fn.lua b/client/data/fn.lua
new file mode 100644
index 0000000..e2fa59e
--- /dev/null
+++ b/client/data/fn.lua
@@ -0,0 +1,120 @@
+--[[
+Functional programming primitives that are occasionally useful
+
+This is not a complete set of primitives, I make them when I need them. Anywhere I use these 
+heavily (where someone unfamiliar with the functional paradigm might get confused)
+I have tried to add comments above or below explaining what it does.
+]]
+local fn = {}
+
+--Returns a function that "stores" the arguments this function was called with
+--For example
+--[[
+local hiprint = fn.curry(print,"[hi]")
+hiprint("world") -- calls print("[hi]","world"), prints "[hi] world"
+]]
+function fn.curry(func,...)
+	local args = {...}
+	return function(...)
+		local nargs = {}
+		for k,v in pairs(args) do nargs[k] = v end
+		for k,v in pairs({...}) do
+			nargs[#nargs + 1] = v
+		end
+		func(table.unpack(nargs))
+	end
+end
+
+--Returns a function that calls all functions starting with the rightmost function
+--and calling the "next" function with the returns of the previous function.
+--The first function can be called with any arguments like normal
+--Anything returned from the last function is returned "out" of this function.
+--Example:
+--
+--local fn = require("fn")
+--local printf = fn.compose(print,string.format)
+--printf("This is %s shit","funky") --prints "This is some funky shit"
+function fn.compose(...)
+	local nargs = {...}
+	local lastresult
+	return function(...)
+		lastresult = {...}
+		for n = #nargs, 1, -1 do
+			lastresult = {nargs[n](table.unpack(lastresult))}
+		end
+		return table.unpack(lastresult)
+	end
+end
+
+--Returns a function that applies the given function on a table called with it.
+--Example:
+--
+--local fn = require("fn")
+--local add_five = fn.map(function(e) return e + 5 end)
+--add_five({1,4,9}) --Returns a table {6,10,14}
+function fn.map(func)
+	return function(tbl)
+		local ret = {}
+		for k,v in pairs(tbl) do
+			ret[k] = func(v)
+		end
+		return ret
+	end
+end
+
+--Returns a function that removes anything NOT matching the given function
+--Example:
+--
+--local fn = require("fn")
+--local important_skills = fn.filter(function(e) return e > 10 end)
+--local usable_skills = imporant_skills({
+--	["wood cutting"] = 5,
+--	["mining"] = 21,
+--	["fighting"] = 12,
+--	["fishing"] = 10,
+--})
+--for k,v in pairs(usable_skills) print(k,":",v) end --prints:
+--mining : 21
+--fighting : 12
+function fn.filter(func)
+	return function(tbl)
+		local ret = {}
+		for k,v in pairs(tbl) do
+			if not func(v) then
+				ret[k] = v
+			end
+		end
+		return ret
+	end
+end
+
+--Get the keys of a table in an array
+function fn.keys(tbl)
+	local ret = {}
+	for k,v in pairs(tbl) do
+		table.insert(ret,k)
+	end
+	return ret
+end
+
+--Get the values of a table in an array
+function fn.values(tbl)
+	local ret = {}
+	for k,v in pairs(tbl) do
+		table.insert(ret,v)
+	end
+	return ret
+end
+
+--Reverses an array
+function fn.reverse(tbl)
+	local ret = {}
+	local len = #tbl
+	for i = 1,len do
+		ret[len - i + 1] = tbl[i]
+	end
+	return ret
+end
+
+
+return fn
-- 
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