prettier printing for FPGroups

src/types.jl

@@ -225,11 +225,20 @@ function FPGroup(
     return FPGroup(G.gens, rels, rws)
 end
 
+function Base.show(io::IO, ::MIME"text/plain", G::FPGroup)
+    print(io, "Finitely presented group generated by:\n\t{")
+    Base.print_array(io, permutedims(gens(G)))
+    println(io, " },")
+    println(io, "subject to relations:")
+    return Base.print_array(io, relations(G))
+end
+
 function Base.show(io::IO, G::FPGroup)
     print(io, "⟨")
-    join(io, gens(G), ", ")
-    print(io, " | ")
-    join(io, relations(G), ", ")
+    Base.print_array(io, permutedims(gens(G)))
+    println(io, " | ")
+    print(io, "\t ")
+    Base.print_array(io, permutedims(relations(G)))
     return print(io, " ⟩")
 end
 

test/AutFn.jl

@@ -96,7 +96,7 @@
         @test evaluate(g*h) == evaluate(h*g)
         @test (g*h).savedhash == zero(UInt)
 
-        @test sprint(show, typeof(g)) == "Automorphism{FreeGroup{Symbol}, …}"
+        @test sprint(show, typeof(g)) == "Automorphism{FreeGroup{Symbol, KnuthBendix.LenLex{Symbol}}, …}"
 
         a = g*h
         b = h*g

test/fp_groups.jl

@@ -14,7 +14,7 @@
     G = FPGroup(F, [a*b=>b*a, a*c=>c*a, b*c=>c*b])
 
     @test G isa FPGroup
-    @test sprint(show, G) == "⟨a, b, c | a*b => b*a, a*c => c*a, b*c => c*b⟩"
+    @test sprint(show, G) == "⟨ a  b  c | \n\t  a*b => b*a  a*c => c*a  b*c => c*b ⟩"
     @test rand(G) isa FPGroupElement
 
     f = a*c*b