Layout based/indentation based lexer

[brendanzab]

Would be nice to have a layout-based syntax like Haskell, Idris, and F#. I'm getting a little sick of all those closing curly braces in Rust!

Resources

• https://www.haskell.org/onlinereport/lexemes.html#sect2.7
• https://www.haskell.org/onlinereport/haskell2010/haskellch10.html#x17-17800010.3
• https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/Parser#Indentation
• Indentation-sensitive parsing (Mark Karpov)
• Layout parsing in pi-forall

[brendanzab]

Plausible thing from Conor McBride on Twitter:

Proposal: layout should be invariant under alpha conversion.
Policy: layout heralds followed by more than one line should be at the end of their line.

So

... where foo x = blah

is ok, but

... where -- line must end here 
    foo True = blah
    foo False = mumble

... will have to think on it though

Anything we do do should still allow us to implement an auto-formatter.