• Subject: Re: [Proposal] Lua-y lambda syntax
• From: "Soni L." <fakedme@...>
• Date: Thu, 27 Apr 2017 14:59:41 -0300

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On 2017-04-27 02:33 PM, Egor Skriptunoff wrote:
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On Thu, Apr 27, 2017 at 5:43 PM, Soni L. <fakedme@gmail.com <mailto:fakedme@gmail.com>> wrote:
```
So, out of all syntax proposals for lambas, I'm surpised nobody
thought of this beauty.

You see, we have `local x = function(a,b,c) return thing end`
syntax. BUT:

1. It's a syntax error to use `function(a,b,c) =thing end`, even
if the REPL accepts `=` as an alias for `return`.
2. Do we need `end` if we restrict it to a single expression?

Combine these 2, and the simplest solution seems to be:

local x = function(a,b,c) = thing

AND we can still get multiple returns:

local x = function(a,b,c) = select(1,a,b,c)
print(x(1, 2, 3)) --> 1, 2, 3

The idea is, function(a,b,c) starts a plain old function. If the
next token is a =, this has to be a lambda. Otherwise it has to be
a function.

There's no ambiguity here since the proposed syntax is currently a
syntax error. It also looks very much like Lua.

The following looks nice:
local swap = function(a,b) = b,a
```
```local swap = (function(a,b) = b), a
```
```
But what does the following nested lambda
local x = function(a,b) = function() = a, b
mean:
local x = function(a,b) = (function() = a, b)
or
local x = function(a,b) = (function() = a), b
?

```
You need to use select() if you want multiple return values. It's a single end-of-list-expr.
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(OT: Sorry for accidentally replying wrong. Some thunderbird update changed the behaviour of the "reply" button so instead of defaulting to reply-to-list I need to actually click the reply-to-list button, which I'm not used to doing.)
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