2/8

The ? Placeholder

Write concise lambdas with Sloplang's implicit function syntax.

The `?` creates an anonymous function on the fly. Instead of writing `x -> x * 2`, you can write `? * 2`. It's shorter and often more readable in pipelines.

-- These are equivalent:
[1, 2, 3] | map x -> x * 2 | print
[1, 2, 3] | map ? * 2 | print

Loading WASM...

When `?` appears multiple times in the same expression, they all refer to the same argument. This is useful for operations that use a value more than once.

-- Square each number
[2, 3, 4] | map ? * ? | print

-- Check if a number is between 3 and 7
[1, 3, 5, 7, 9] | where ? >= 3 and ? <= 7 | print

Loading WASM...

You can use `?` with field access and indexing. This is handy for working with structured data.

let people = [
	{ name: "Alice", age: 30 },
	{ name: "Bob", age: 25 },
	{ name: "Carol", age: 35 },
]

people | order_by ?.age | map ?.name | print

Loading WASM...

Unary operators work with `?` too. A common pattern is `-?` for descending sort.

-- Sort descending
[3, 1, 4, 1, 5, 9] | order_by -? | print

-- Negate a predicate
[true, false, true] | where !? | print

Loading WASM...