Add isuppercase, islowercase, uppercasefirst and lowercasefirst (#516)

Author: nalimilan

README.md

@@ -382,6 +382,9 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `LinSpace` is now `LinRange` ([#25896]).
 
+* `isupper`, `islower`, `ucfirst` and `lcfirst` are now `isuppercase`, `islowercase`,
+  `uppercasefirst` and `lowercasefirst` ([#26442]).
+
 ## New macros
 
 * `@__DIR__` has been added ([#18380])
@@ -596,3 +599,4 @@ includes this fix. Find the minimum version from there.
 [#26149]: https://github.com/JuliaLang/julia/issues/26149
 [#26156]: https://github.com/JuliaLang/julia/issues/26156
 [#26316]: https://github.com/JuliaLang/julia/issues/26316
+[#26442]: https://github.com/JuliaLang/julia/issues/26442

src/Compat.jl

@@ -1679,6 +1679,14 @@ else
     const indexin = Base.indexin
 end
 
+if VERSION < v"0.7.0-DEV.4585"
+    export isuppercase, islowercase, uppercasefirst, lowercasefirst
+    const isuppercase = isupper
+    const islowercase = islower
+    const uppercasefirst = ucfirst
+    const lowercasefirst = lcfirst
+end
+
 include("deprecated.jl")
 
 end # module Compat

test/runtests.jl

@@ -1491,4 +1491,12 @@ end
 # 0.7.0-DEV.3972
 @test Compat.indexin([1, 2], [1, 0, 1]) == [1, nothing]
 
+# 0.7.0-DEV.4585
+@test isuppercase('A')
+@test !isuppercase('a')
+@test islowercase('a')
+@test !islowercase('A')
+@test uppercasefirst("qwerty") == "Qwerty"
+@test lowercasefirst("Qwerty") == "qwerty"
+
 nothing