Feature: Add Missing overloads (#10)

src/ClausenFunctions.jl

@@ -10,6 +10,7 @@ include("Cl4.jl")
 include("Cl5.jl")
 include("Cl6.jl")
 include("Cl.jl")
+include("Missing.jl")
 include("Series.jl")
 include("Sl.jl")
 

src/Missing.jl

@@ -0,0 +1,7 @@
+for f in (:cl1, :cl2, :cl3, :cl4, :cl5, :cl6)
+    @eval $(f)(::Missing) = missing
+end
+
+for f in (:cl, :sl)
+    @eval $(f)(::Integer, ::Missing) = missing
+end

test/Missing.jl

@@ -0,0 +1,13 @@
+@testset "Missing" begin
+    @test ismissing(ClausenFunctions.cl1(missing))
+    @test ismissing(ClausenFunctions.cl2(missing))
+    @test ismissing(ClausenFunctions.cl3(missing))
+    @test ismissing(ClausenFunctions.cl4(missing))
+    @test ismissing(ClausenFunctions.cl5(missing))
+    @test ismissing(ClausenFunctions.cl6(missing))
+
+    for n in -16:16
+        @test ismissing(ClausenFunctions.cl(n, missing))
+        @test ismissing(ClausenFunctions.sl(n, missing))
+    end
+end

test/runtests.jl

@@ -9,5 +9,6 @@ include("Cl4.jl")
 include("Cl5.jl")
 include("Cl6.jl")
 include("Cl.jl")
+include("Missing.jl")
 include("Sl.jl")
 include("range_reduction.jl")