Require JSON instead of using Requires (#189)

Loading JSON is actually faster than using Requires.

Author: nalimilan

Project.toml

@@ -5,14 +5,13 @@ version = "0.5.3"
 [deps]
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
 Future = "9fa8497b-333b-5362-9e8d-4d0656e87820"
+JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
 Missings = "e1d29d7a-bbdc-5cf2-9ac0-f12de2c33e28"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
-Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 
 [extras]
-JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["JSON", "Test"]
+test = ["Test"]

src/CategoricalArrays.jl

@@ -12,7 +12,7 @@ module CategoricalArrays
     export cut, recode, recode!
 
     using Compat
-    using Requires
+    using JSON
     using Reexport
 
     # TODO: cannot @reexport in conditional, the below should be removed when 0.6 is deprecated
@@ -22,12 +22,6 @@ module CategoricalArrays
         using Printf
     end
 
-    function __init__()
-        # JSON of CatValue is JSON of the value it refers to
-        @require JSON="682c06a0-de6a-54ab-a142-c8b1cf79cde6" JSON.lower(x::CatValue) =
-            JSON.lower(get(x))
-    end
-
     include("typedefs.jl")
 
     include("buildfields.jl")

src/value.jl

@@ -215,6 +215,9 @@ end
 Base.:<(y::AbstractString, x::CatValue) = invoke(<, Tuple{Any, CatValue}, y, x)
 Base.:<(::Missing, ::CatValue) = missing
 
+# JSON of CatValue is JSON of the value it refers to
+JSON.lower(x::CatValue) = JSON.lower(get(x))
+
 # AbstractString interface for CategoricalString
 Base.string(x::CategoricalString) = get(x)
 Base.eltype(x::CategoricalString) = Char