diff -r 11ae9103f59d -r 77cd7b8fb6a6 mypath.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mypath.lua	Mon Jul 06 12:35:38 2020 -0500
@@ -0,0 +1,113 @@
+
+--@module path
+local path={}
+
+local tuple=require("tuple")
+local lfs=require("lfs")
+local err=require("err")
+local config=require("config")
+
+local sep=config.dirsep
+
+function path.join(p, f)
+    if p=="" then
+        return f
+    else
+        return p..sep..f
+    end
+end
+
+function path.dirbasename(p)
+    local d, b = string.match(p,
+        "^(.*)"..sep.."+([^"..sep.."]+)"..sep.."*$")
+    if not b then
+        return "", p
+    else
+        return d, b
+    end
+end
+
+function path.dirname(p)
+    return tuple.fst(dirbasename(p))
+end
+
+function path.dirname_slash(p)
+    local dn=dirname(p)
+    if dn=="" then
+        return dn
+    else
+        return dn..sep
+    end
+end
+
+function path.basename(p)
+    return tuple.snd(dirbasename(p))
+end
+
+function path.rmext(p)
+    return string.gsub(p, "%.[^.]*$", "")
+end
+
+-- would rather do this as an iterator, but can't
+-- coroutine.yield from gsub handler
+function path.split(p)
+    local t={}
+    local head=""
+    local s, p2 = string.match(p, "^("..sep.."+)(.*)$")
+    if s then
+        table.insert(t, "/.") -- root
+        p=p2
+    end
+    string.gsub(p, "([^"..sep.."]+)", --..sep.."+", 
+            function(d) table.insert(t, d); end)
+    return t
+end
+
+--[[
+function path.parts(p)
+    local s={i=1, t=split(p)}
+    local function g(s)
+        local v=s.t[s.i]
+        s.i=s.i+1
+        return v
+    end
+    return g, s
+end
+
+function path.makepath(p, head)
+    head=head or ""
+    for d in parts(p) do
+        head=head..d
+        local a=lfs.attributes(head)
+        if not a then
+            local success, e = lfs.mkdir(head)
+            if not success then
+                err.file(head, e)
+            end
+        elseif a.mode~="directory" then
+            err.file(head, "not a directory")
+        end
+        head=head..sep
+    end
+end
+]]
+
+function path.simplify(p)
+    local capts={}
+    local start=string.match(p, "^(/)")
+    string.gsub(p, "([^/]+)",
+    function(e)
+        if e==".." and #capts > 1 then
+            capts[#capts]=nil
+        elseif e~="." then
+            table.insert(capts, e)
+        end  
+    end)
+    return (start or "")..table.concat(capts, "/")
+end
+
+function path.to_root(p)
+    return string.rep("../",#(path.split(p))-1)
+end
+
+return path