Composition operator [was: Re: Records in Haskell]

Evan Laforge qdunkan at
Thu Jan 12 19:41:43 CET 2012

>> I told you so (^_^)
>> Unicode dot (∘) would be optimal, since that's what it's for. If to
>> type '∘' is awkward, then one can use (Control.Category.<<<). We need
>> not (and, in my opinion, should not) define another operator.
> Is ∘ (U+2218 RING OPERATOR)* in Prelude yet? We should propose that.**
> I checked my compose-key (Linux)
> and it can produce middle-dot · (U+00B7 MIDDLE DOT) with "Compose . -", but
> not ∘ in any way***.  If we use the proper Unicode operator ∘, then let's

OS X makes a MIDDLE DOT with option-shift-9: ·

However, changing the composition operator from (.) will involve huge
amounts of changes to source code.  It can mean changing a large
percentage of all the lines in each file---I for one use (.) quite
heavily.  With a haskell parser the rename could happen automatically,
but we're still talking about a wall in source control where every
single line was changed by one person.  Groups that are reluctant to
make formatting changes for fear of confusing revision history are
really going to hate that one.

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