CODEWITHSUNDEEP
programming-languagesoperators
Sled
Sled

Reputation: 18949

Which programming languages allow you to define paired-bracket like operators?

I am looking to create a DSL and I'm looking for a language where you can define your own bracket-style operators for things like the floor and ceiling functions. I'd rather not go the route of defining my own Antlr parser for a custom syntax.

As a far as I know the only languages I know of that allow you to define custom operators are all binary infix operators.

tl;dr: Which languages allow for defined paired symbol (like opening bracket/closed bracket) operators?

Also, I don't see how this question can be "too broad" if no one has named a single language that has this and the criteria are very specific and definitely in the programming domain.

Upvotes: 2

Views: 176

Answers (1)

Ingo
Ingo

Reputation: 36339

Since Fortress is dead, the only languages I know of where something like this would be imaginable are those of FORTH heritage.

In all others that I know of, braces, brackets and parentheses are already heavily used, and can't be overloaded further.

I suggest giving up the quest for such stuff and get comfortable writing

floor x
ceiling y

or however function application is expressed in the language of your choice.

However, in the article you cite, it is said: Unicode contains codepoints for these symbols at U+2308–U+230B: ⌈x⌉, ⌊x⌋.

Thus you can at least define this a s operator in a Haskell like language and use like:

infix 5 ⌈⌉
(foo ⌈⌉)

The best I could come up with is like the following:

--- how to make brackets
module Test where

import Prelude.Math

infix 7 `«`
infix 6 `»`

_ « x = Math.ceil x
(»)     = const

x = () «2.345» ()

main _ = println x

The output was: 3.0 (This is not actually Haskell, but Frege, a Haskell-like JVM language.)

Note that I used «» instead of ⌈⌉, because I somehow have no font in my IDE that would correctly show the bracket symbols. (This is another reason not to do such.)

The way it works is that with the infix directives, we get this parsed as

 (»)  ((«) () 2.345)  ()

(One could insert any expression in place of the ())

Maybe if you ask in the Haskell group, someone finds a better solution.

Upvotes: 3

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