From f2d2d4ee527ddd59fe461c2a60b74506ca931696 Mon Sep 17 00:00:00 2001
From: Marek Kaluba <kalmar@amu.edu.pl>
Date: Sat, 18 Dec 2021 19:34:04 +0100
Subject: [PATCH] prettier printing for FPGroups

---
 src/types.jl      | 17 +++++++++++++----
 test/AutFn.jl     |  2 +-
 test/fp_groups.jl |  2 +-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/types.jl b/src/types.jl
index 4855192..a5002ae 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -225,12 +225,21 @@ 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), ", ")
-    return print(io, "⟩")
+    Base.print_array(io, permutedims(gens(G)))
+    println(io, " | ")
+    print(io, "\t ")
+    Base.print_array(io, permutedims(relations(G)))
+    return print(io, " ⟩")
 end
 
 Base.show(io::IO, ::Type{<:FPGroup{T}}) where {T} =
diff --git a/test/AutFn.jl b/test/AutFn.jl
index c9b47c5..793b685 100644
--- a/test/AutFn.jl
+++ b/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
diff --git a/test/fp_groups.jl b/test/fp_groups.jl
index 4e4f624..0fb5b1e 100644
--- a/test/fp_groups.jl
+++ b/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