Fixes

src/show.jl

@@ -21,7 +21,7 @@ function print_coefficient(io::IO, ::MIME"text/latex", coeff::AbstractFloat)
     return print(io, s)
 end
 
-trim_LaTeX(::MIME, s::AbstractString) = s
+trim_LaTeX(_, s::AbstractString) = s
 
 function trim_LaTeX(::MIME"text/latex", s::AbstractString)
     i = firstindex(s)
@@ -52,12 +52,17 @@ end
 # Since they add `$$` around it, we need to trim it with `trim_LaTeX`
 function print_coefficient(io::IO, mime, coeff)
     print(io, "(")
-    if showable(mime, coeff)
-        print(io, trim_LaTeX(mime, sprint(show, mime, coeff)))
+    print_mime(io, mime, coeff)
+    print(io, ")")
+    return
+end
+
+function print_mime(io::IO, mime, x)
+    if showable(mime, x)
+        print(io, trim_LaTeX(mime, sprint(show, mime, x)))
     else
-        show(io, coeff)
+        show(io, x)
     end
-    return print(io, ")")
 end
 
 isnegative(x::Real) = x < 0
@@ -70,7 +75,7 @@ function _coeff_elt_print(io, mime, c, elt)
     print_coefficient(io, mime, c)
     _print_dot(io, mime)
     __needs_parens(elt) && print(io, '(')
-    print(io, trim_LaTeX(mime, sprint(show, mime, elt)))
+    print_mime(io, mime, elt)
     __needs_parens(elt) && print(io, ')')
     return
 end

test/constructors.jl

@@ -1,3 +1,13 @@
+struct CustomLaTeXPrint
+    s::String
+end
+
+Base.:-(s::CustomLaTeXPrint) = s
+Base.iszero(::CustomLaTeXPrint) = false
+function Base.show(io::IO, ::MIME"text/latex", s::CustomLaTeXPrint)
+    return print(io, s.s)
+end
+
 @testset "Algebra and Elements" begin
     alph = [:a, :b, :c]
     A★ = FreeWords(alph)
@@ -81,6 +91,10 @@
     @test sprint(show, Z) == "2.0·(id) + 1.0·b·c"
     @test sprint(show, 2one(RG) - RG(p)) == "2·(id) - 1·b·c"
     @test sprint(show, (2 + im) * one(RG) - (3im) * RG(p)) == "(2 + 1im)·(id) + (0 - 3im)·b·c"
+
+    @test sprint(print, (2 + im) * one(RG) - (3im) * RG(p)) == "(2 + 1im)·(id) + (0 - 3im)·b·c"
+    @test sprint(show, 1e-9 * one(RG)) == "1.0e-9·(id)"
+    @test sprint((io, x) -> show(io, "text/latex", x), 1e-9 * one(RG)) == "\$\$ 1.0 \\cdot 10^{-9} \\cdot (id) \$\$"
 
     @test LinearAlgebra.norm(a, 1) == 3
 
@@ -93,4 +107,14 @@
     @test deepcopy(a) !== a
     @test coeffs(deepcopy(a)) !== coeffs(a)
     @test parent(deepcopy(a)) === parent(a)
+
+    latex = CustomLaTeXPrint(" \$\$ \\[\\(α_β∀ \\) \\]\t  \$\$")
+    @test sprint((io, x) -> show(io, "text/latex", x),
+        SA.AlgebraElement(SA.SparseCoefficients([p], [latex]), RG)) ==
+          "\$\$ (α_β∀) \\cdot b·c \$\$"
+    # Test that the check for `\\)` handles unicode well
+    latex = CustomLaTeXPrint("\\(β∀")
+    @test sprint((io, x) -> show(io, "text/latex", x),
+        SA.AlgebraElement(SA.SparseCoefficients([p], [latex]), RG)) ==
+          "\$\$ (\\(β∀) \\cdot b·c \$\$"
 end