‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, December 5th, 2021 at 8:13 AM, Tom Ellis
On Sun, Dec 05, 2021 at 02:02:09PM +0000, Adrian via Haskell-Cafe wrote:
In the Data.Monoid library there is a monoid type instance for Endo
a that is described in the following manner:
The monoid of endomorphisms under composition.
I understand how it is a monoid of endofunctions, but am unclear on
how it is a monoid of endomorphisms.
I'm not sure what you mean. The morphisms in this case are exactly
functions. "Endomorphism" and "endofunction" have the same meaning in
this context.
Tom
According to Algebra [Hungerford 74], an endomorphism is an endofunction that is a homomorphism. A set of endomorphisms is quite distinct from a set of endofunctions in this regard.