Simplify env filtering

Author: JoaquinTrinanes

cookbook/direnv.md

@@ -18,7 +18,7 @@ let-env config = {
   hooks: {
     pre_prompt: [{ ||
         let direnv = (direnv export json | from json | default {})
-        let env_to_convert = ($direnv | transpose key value | where key in ($env.ENV_CONVERSIONS | columns))
+        let env_to_convert = ($direnv | transpose key value | where key in $env.ENV_CONVERSIONS)
         let converted_values = ($env_to_convert | each {|it|
             let convert = ($env.ENV_CONVERSIONS | get $it.key | get from_string)
             let value = (do $convert $it.value)