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Comment by christophilus | Hacker News Reader

Crystal is interesting-- I've followed it at a distance-- but from what I understand, it's not really functional. Persistent data structures aren't a first-class citizen, and it seems to prefer blocks to lambdas. Also, (unrelated to the functional thing), the compiler isn't super fast. I think a really fast edit -> save -> compile -> reload time is one of the defining features of OCaml and Go.

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> it seems to prefer blocks to lambdas

What does this mean?

Crystal prefers these constructs [0] `foo.map {|x| x + 1}` where the stuff between the squiggles is called a "block". I come from Ruby, so maybe Crystal got this one right, but Ruby blocks, at least, are a more limited, less general-purpose approach to lambdas (by which I mean anonymous, first-class functions + closures) [1].

[0] https://crystal-lang.org/docs/syntax_and_semantics/blocks_an...

[1] https://docs.microsoft.com/en-us/dotnet/csharp/programming-g...

Crystal has lambdas w/closures (called Proc) with `->{ 1 }` syntax [0]. Because of ruby-like syntax where `foo` is a call if `foo` is a function you need to do `foo.call` on those lambdas explicitly - so you can distinguish between passing them around as values `foo` and calling them `foo.call` or `foo.call(arg1, arg2, ...)`.

I've played with it a bit, haven't seen problems with compile times, they were actually pretty good.

The nice thing about Crystal is that it is extremely easy to use, terse code, easy macros, fast executables, algebraic types, good packaging story - in general very good ergonomy.

I hope it'll pick up one day.

[0] https://crystal-lang.org/docs/syntax_and_semantics/literals/...

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