# Are any of these bugs?
**URL:** https://discourse.julialang.org/t/are-any-of-these-bugs/3569
**Category:** General Usage
**Created:** [May 6, 2017, 11:23pm UTC](https://discourse.julialang.org/t/are-any-of-these-bugs/3569 "2017-05-06T23:23:17Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@loisel](https://discourse.julialang.org/u/loisel)
#### Post date: [May 6, 2017, 11:23pm UTC](https://discourse.julialang.org/t/are-any-of-these-bugs/3569/1 "2017-05-06T23:23:17Z")
julia\> immutable Z \<: Unsigned
foo
end
julia\> Z(12)
Error showing value of type Z:
ERROR: MethodError: no method matching leading\_zeros(::Z)
Closest candidates are:
leading\_zeros{T\<:Union{Int128,Int16,Int32,Int64,Int8,UInt128,UInt16,UInt32,UInt64,UInt8}}(::T\<:Union{Int128,Int16,Int32,Int64,Int8,UInt128,UInt16,UInt32,UInt64,UInt8}) at int.jl:150
in hex(::Z, ::Int64, ::Bool) at ./intfuncs.jl:303
in display(::Base.REPL.REPLDisplay{Base.REPL.LineEditREPL}, ::MIME{Symbol(“text/plain”)}, ::Z) at ./REPL.jl:132
in display(::Base.REPL.REPLDisplay{Base.REPL.LineEditREPL}, ::Z) at ./REPL.jl:135
in display(::Z) at ./multimedia.jl:143
in print\_response(::Base.Terminals.TTYTerminal, ::Any, ::Void, ::Bool, ::Bool, ::Void) at ./REPL.jl:154
in print\_response(::Base.REPL.LineEditREPL, ::Any, ::Void, ::Bool, ::Bool) at ./REPL.jl:139
in (::Base.REPL.##22#23{Bool,Base.REPL.##33#42{Base.REPL.LineEditREPL,Base.REPL.REPLHistoryProvider},Base.REPL.LineEditREPL,Base.LineEdit.Prompt})(::Base.LineEdit.MIState, ::Base.AbstractIOBuffer{Array{UInt8,1}}, ::Bool) at ./REPL.jl:652
in run\_interface(::Base.Terminals.TTYTerminal, ::Base.LineEdit.ModalInterface) at ./LineEdit.jl:1579
in run\_interface(::Base.Terminals.TTYTerminal, ::Base.LineEdit.ModalInterface) at /Applications/Julia-0.5.app/Contents/Resources/julia/lib/julia/sys.dylib:?
in run\_frontend(::Base.REPL.LineEditREPL, ::Base.REPL.REPLBackendRef) at ./REPL.jl:903
in run\_repl(::Base.REPL.LineEditREPL, ::Base.##930#931) at ./REPL.jl:188
in \_start() at ./client.jl:360
in \_start() at /Applications/Julia-0.5.app/Contents/Resources/julia/lib/julia/sys.dylib:?
julia\> Base.:==(a::Z,b::Z) = “hello, world”
ERROR: syntax: invalid identifier name “:=”
julia\> Base.isequal(a::Z,b::Z) = “hello, world”
julia\> Z(12)==Z(13)
false
julia\> isequal(Z(12),Z(13))
“hello, world”
---
### Author:  [@yuyichao](https://discourse.julialang.org/u/yuyichao)
#### Post date: [May 6, 2017, 11:59pm UTC](https://discourse.julialang.org/t/are-any-of-these-bugs/3569/3 "2017-05-06T23:59:30Z")
None of these are behavioral bugs though it is currently not extremely clear on what method needs to be extended when implementing certain kind of types so you could say it’s interface documentation bugs.
---
### Author:  [@loisel](https://discourse.julialang.org/u/loisel)
#### Post date: [May 7, 2017, 3:05pm UTC](https://discourse.julialang.org/t/are-any-of-these-bugs/3569/4 "2017-05-07T15:05:40Z")
OK thanks. I mean, I can create an Unsigned type that does not cause these problems but I find it an odd design choice that subtyping Unsigned automatically breaks the P in REPL.