Merge pull request #14 from JuliaAlgebra/bl/convintmono

Add conversion from Int to Monomial

src/mono.jl

@@ -24,6 +24,12 @@ Monomial{C}() where C = Monomial{C}(PolyVar{C}[], Int[])
 Monomial(vars::TupOrVec{PolyVar{C}}, z::Vector{Int}) where C = Monomial{C}(vars, z)
 Monomial{C}(x::PolyVar{C}) where C = Monomial{C}([x], [1])
 Monomial(x::PolyVar{C}) where C = Monomial{C}(x)
+function Monomial{C}(α) where C
+    α == 1 || error("Cannot convert $α to a Monomial{$C} as it is not one")
+    Monomial{C}(PolyVar{C}[], Int[])
+end
+# defaults to commutative so that `Monomial(1)` is consistent with TypedPolynomials
+Monomial(α) = Monomial{true}(α)
 
 Base.copy(m::M) where {M<:Monomial} = M(m.vars, copy(m.z))
 

test/mono.jl

@@ -25,6 +25,15 @@
         @test zeroterm(Monomial{false}) == 0
         @test zero(Monomial{false}) == 0
         @test one(Monomial{true}) == 1
+        @test_throws ErrorException Monomial(2)
+        @test (@inferred Monomial(1)) isa Monomial{true}
+        @test Monomial(1) == 1
+        @test_throws ErrorException Monomial{true}(2)
+        @test (@inferred Monomial{true}(1)) isa Monomial{true}
+        @test Monomial{true}(1) == 1
+        @test_throws ErrorException Monomial{false}(2)
+        @test (@inferred Monomial{false}(1)) isa Monomial{false}
+        @test Monomial{false}(1) == 1
         @polyvar x
         @test_throws ArgumentError Monomial{true}([x], [1,0])
         @test zeroterm(x^2) isa Term{true, Int}