Haskell records in 2025 (Haskell Unfolder #45)

[atravers]

@AntC2

Using . for compose (and not insisting it be space-surrounded - discussed in the video about 13:30) was always going to end in tears. There’s a 1999 paper from Jones and Jones proposing using some other glyph for compose, so that . is reserved for qualified names and record access.

…and since that alternative for . apparently went nowhere:

and (o)   _f _g _x = _f (_g _x)

hbc/src/lib/Ppre.m, line 35

Translated into Haskell:

infixr 9 `o`
o :: (b -> c) -> (a -> b) -> a -> c
(f `o` g) x = f (g x)

…since no-one here seems to have any great problem with “infix-quoting” the likes of div, mod, divMod, quot, rem, quotRem, et al.

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@AntC2

GHC can’t keep up with an approach developed in the 1970’s, nor with a Haskell that’s gotten no love in the past 20 years?

Since you’ve apparently forgotten how this topic ended:

@atravers

So the answer to the questions in your original post:

@AntC2

I can’t find any explanation/rationale for why Haskell’s records are so different vs SML. Does anyone know of any refs? Or can give some explanations?

…then must surely be something like:

It would improve the language to fix this. But this hasn’t risen to the level where it’s worth […] spending the cycles to fix the problem. That said, I’d welcome work in this direction.

Richard Eisenberg

…as opposed to:

@AntC2

[…] GHC doesn’t care.

Q.E.D.

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@AntC2

There are already too many Haskell-alike languages with better record syntax. (Even ML, which had sensible syntax before Haskell was a thing.)

From FOLDOC:

lazy sml2c

A lazy version sml2c. Portable, written in SML. Language extensions include first-class continuations, asynchronous signal handling.E-mail: david.tarditi@cs.cmu.edu. ftp://dravido.soar.cs.cmu.edu/usr/nemo/sml2c.

Lazy Standard ML

<language>

(LSML) A lazy varient of SML, allowing cyclic val definitions, by Prateek Mishra mishra@sbcs.sunysb.edu.

Enjoy.