Less verbose lambda syntax

[SamahParticipant]

Monkey

[crayon-5cba161cada8e566665862 inline="true" ]' existing syntax Local foo := Lambda:Int(x:Int) Return x + 2 End Print(foo(5)) ' slightly less verbose (note inferred return statement for single line expression) Local foo := Lambda:Int(x:Int) x + 2 End ' even simpler, with type inference for the return value Local foo := Lambda(x:Int) x + 2 End ' allows for very clean sorting code ' note that Sort expects Int(T,T), so it can be completely inferred Local foo := New Stack<Int>() foo.Sort(Lambda(lhs,rhs) lhs <=> rhs End)

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[crayon-5cba161cada8e566665862 inline="true" ]' existing syntax Local foo := Lambda:Int(x:Int)    Return x + 2 End Print(foo(5))   ' slightly less verbose (note inferred return statement for single line expression) Local foo := Lambda:Int(x:Int) x + 2 End   ' even simpler, with type inference for the return value Local foo := Lambda(x:Int) x + 2 End   ' allows for very clean sorting code ' note that Sort expects Int(T,T), so it can be completely inferred Local foo := New Stack<Int>() foo.Sort(Lambda(lhs,rhs) lhs <=> rhs End)

[/crayon]

Thoughts, before I fork and pull request?

[Mark SiblyKeymaster]

Probably not gonna accept it – I ‘m fine with current syntax and find ‘shortcut’ lambdas one of the hardest things to read in other languages.

[SamahParticipant]

Sorry, I’m not quite clear on your response. Was that “accept the pull request” or “accept the existing syntax”?
One of the more powerful uses of lambdas/closures is to represent a very simple piece of logic (even one expression) as a first-class type. If the lambda in question is as simple as a comparison or equation, I think the condensed one-line syntax is quite acceptable.
If the lambda has a lot of logic to it (event handlers, etc.) then it makes sense to spread it across as many lines as you need, as per the current syntax.

[Mark SiblyKeymaster]

Sorry, that should have been ‘not’ – it was late.

Maybe it’s just my inexperience with lambdas, but the short form looks like a minor ‘win’ at the cost of making the code look a lot more obsfucated. It’s just not very monkey-like IMO.

Maybe it’ll grow on me (it has a tiny bit) but right now I just don’t see the need for it.

[wiebowParticipant]

TBH, I find this unreadable… If you want to return something, why not state it?

[SamahParticipant]

TBH, I find this unreadable… If you want to return something, why not state it?

The idea is less about the implicit return statement and more about keeping a simple lambda on a single line.
With a return statement and no inferred types it’s still quite legible. It just makes it much cleaner if you want to pass a single expression as a parameter to a function.

Monkey

[crayon-5cba161cb9e55315743278 inline="true" ]' Single line: SomeMethod(Lambda:Int(x:Int) Return x + 1 End) ' As opposed to: SomeMethod(Lambda:Int(x:Int) Return x + 1 End)

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[crayon-5cba161cb9e55315743278 inline="true" ]' Single line: SomeMethod(Lambda:Int(x:Int) Return x + 1 End) ' As opposed to: SomeMethod(Lambda:Int(x:Int)   Return x + 1 End)

[/crayon]

Maybe it’ll grow on me (it has a tiny bit) but right now I just don’t see the need for it.

If I add flatmap/filter/reduce to the Stack class and provide an example banana project, you’ll see the power of mini-closures and why it makes code much easier to understand. I’ve already added it, I’ll make a PR at some point.

[Mark SiblyKeymaster]

Think I prefer ‘as opposed to’.

The problem I have with the first one is it’s just a string of ‘stuff’. At least in c++ you get the enclosing ‘{‘ ‘}’ to delimit the lambda scope from the expression scope, even if it’s on the same line.

[SamahParticipant]

How hard would it be to tell the parser to make newlines optional for single statement lambdas, then? That should be a simple enough change, and if the developer prefers to split it across multiple lines, that’s up to them.

[dmazParticipant]

At least in c++ you get the enclosing ‘{‘ ‘}’ to delimit the lambda scope from the expression scope

isn’t that what Lambda() and End are for?

[SamahParticipant]

isn’t that what Lambda() and End are for?

Pretty much, but the majority of the Monkey-X/MX2 community have an aversion to braces.

[SamahParticipant]

I’ll assume that’s a no, then.

[Mark SiblyKeymaster]

Yes, that’s a no.

I was initially planning on supporting ‘looser’ eol rules, but that wasn’t as easy as I thought it’d be.

In the end, I sorted of just embraced the whole strict eol approach instead, thinking I might revisit it later. But now, I just don’t see a compelling reason to any more – I like it the way it is.

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