[epolanski]

Typescript has a hole type too implemented in fp-ts and effect-ts.

Super useful for when you don't know what are you missing and get a type signature for it.

It's mostly useful for when you declare some `const foo: (bar: Bar) => Whatever` and in the midst of your implementation you don't know what you're missing.

Requires an advanced level in TS to be used to the max.

https://gcanti.github.io/fp-ts/modules/function.ts.html#hole

https://effect-ts.github.io/effect/effect/Function.ts.html#h...

[disconcision]

there's this hacky quick way of partially emulating typed holes sans library too: https://dev.to/gcanti/type-holes-in-typescript-2lck

we (team hazel) recently used that device in our typescript version of a hazel setup for typed-hole-contextualized code completion as described in https://dl.acm.org/doi/10.1145/3689728

[williamdclt]

I’m struggling to understand the use, do you have a concrete example?

[dietr1ch]

Brady has a presentation about Idris where he shows Type-Driven development (where you write code that could typecheck with some holes and you get the compiler to help you figure out the missing types for your "whatever/something" untyped variables)

https://youtu.be/X36ye-1x_HQ?t=5m15s

[LandR]

This is awesome, but I find that syntax so hard to follow, but that's just me being unfamiliar with it I guess.

[dietr1ch]

It happens, but all syntax families eventually become familiar, even on LISP you eventually stop worrying about the parentheses as you learn how to grok the code.

[epolanski]

Suppose you declare some:

const transformFoo: (foos: Foo[]) => Bar

and you start implementing it and get stuck with some callback or whatever you can put a `hole` and it will tell you the type signature of what you're missing.