2 ms·

I don't mind indentation based languages. I used to hate them, but they've grown on me after using python, Haskell, Idris, Agda, etc. And I ended up making my o

by dunham 2mo ago

I don't mind indentation based languages. I used to hate them, but they've grown on me after using python, Haskell, Idris, Agda, etc. And I ended up making my own language indentation based (it is similar to Idris). That said, it is hard-mode: - You'll have to figure out how to parse it. - If you want editor support, it's a pain to get tree-sitter to handle it. - You may not be able to pull off editor operations like "rename" without implementing a pretty printer (a rename might affect indentation). I think it is helpful for crude error recovery. On parse error, my language will simply skip to the next column 0 token and parse another declaration. I did not do this (hindsight), but I would recommend arranging the grammar so you only get indented blocks in cases where the previous line ends in a keyword that introduces it. I think python has a trailing `:` every time indentation is introduced, and Elm does this too - in statements like `let` you need a newline after the `let` to get the multi-declaration version. (This addresses the rename issue.)

floxy 2mo ago
>a rename might affect indentation I think I need to see an example.
- dunham 2mo ago
  It happens when the indentation is established on the same line as other code, so having a rule that you need a newline to start indentation will avoid the issue. Examples from haskell: foo x y = do a <- something pure somethingElse Renaming `x` to `xxx` would push the indented block in and the subsequent lines would have to be indented too. Similarly: foo x y = let a = something b = anotherThing in somethingElse Elm avoids this by requiring an newline after the `do` and `let` (if the `let` has multiple assignments). Edit: This was brought to my attention by an Idris style guide that said: "Indent so that alpha conversion always works with a simple search and replace. In general this would mean starting a new line when starting a new level of indentation."
  - floxy 2mo ago
    Thanks

by dunham 2mo ago

floxy 2mo ago

>a rename might affect indentation I think I need to see an example.

dunham 2mo ago
It happens when the indentation is established on the same line as other code, so having a rule that you need a newline to start indentation will avoid the issue. Examples from haskell: foo x y = do a <- something pure somethingElse Renaming `x` to `xxx` would push the indented block in and the subsequent lines would have to be indented too. Similarly: foo x y = let a = something b = anotherThing in somethingElse Elm avoids this by requiring an newline after the `do` and `let` (if the `let` has multiple assignments). Edit: This was brought to my attention by an Idris style guide that said: "Indent so that alpha conversion always works with a simple search and replace. In general this would mean starting a new line when starting a new level of indentation."
- floxy 2mo ago
  Thanks