Extend Cols API (#42)

Author: bkamins

Project.toml

@@ -1,7 +1,7 @@
 name = "DataAPI"
 uuid = "9a962f9c-6df0-11e9-0e5d-c546b8b5ee8a"
 authors = ["quinnj <[email protected]>"]
-version = "1.8.0"
+version = "1.9.0"
 
 [compat]
 julia = "1"

src/DataAPI.jl

@@ -161,8 +161,12 @@ end
 
 """
     Cols(cols...)
+    Cols(f::Function)
 
 Select the union of the selections in `cols`. If `cols == ()`, select no columns.
+
+If the only positional argument is a `Function` `f` then select the columns whose
+names passed to the `f` predicate as strings return `true`.
 """
 struct Cols{T<:Tuple}
     cols::T