30 Jun 08:59 2013

## A possible alternative to dot notation for record access

Judah Jacobson <judah.jacobson <at> gmail.com>

2013-06-30 06:59:53 GMT

2013-06-30 06:59:53 GMT

Hi all,

I had a quick idea about record field syntax as specified in the GSoC project plan: http://hackage.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/Plan.

I had a quick idea about record field syntax as specified in the GSoC project plan: http://hackage.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/Plan.

Instead of "f.x" (to access field x of record f), maybe we could write "f{x}" as the record selection. That is, we'd reuse the brace notation which is already in place for record updates. Unlike dot notation, this is unambiguous and doesn't conflict with any existing syntax (AFAIK). It would also generalize to "f{x}{y}{z}" instead of "f.x.y.z".

This proposal would add two new forms of expressions:

f{x} to access field x of data f

({x}) = \f -> f{x} as a field access section

Additionally, it seems like record mutation expressions could also have sections:

({x=2}) = \f -> f{x=2}

That actually seems useful by itself, regardless of whether we use dot notation for field access.

Best,

-Judah

This proposal would add two new forms of expressions:

f{x} to access field x of data f

({x}) = \f -> f{x} as a field access section

Additionally, it seems like record mutation expressions could also have sections:

({x=2}) = \f -> f{x=2}

That actually seems useful by itself, regardless of whether we use dot notation for field access.

Best,

-Judah

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