Partial Type Argument Inference

type.ts

declare function get<Doc, Key extends keyof Doc = infer>();
declare let unknownObj: unknown;
declare let obj: { title: string; description: string };

// CASE 0
const case0 = get(obj, 'description'); 
// Unchanged: string

// CASE 1
const case1 = get<{ title: string; description: string }>(unknownObj, 'description'); 
// Current: TS Error
// Proposal: string

// CASE 2
const case2 = get<{ title: string; description: string }, 'title'>(unknownObj, 'description');
// Current: ❌ missing type argument
// Proposal: ❌ 'description' cannot be assigned to 'title'

// CASE 3
// Currently, you have to write
declare function floatingGenericTypeArgument<A, B = any>(b: B): [A, B]

// With this proposal, you could write
declare function floatingGenericTypeArgument<A, B = infer>(b: B): [A, B]

const case3 = floatingGenericTypeArgument<'a'>(null);
// Current: ['a', any]
// Proposal: ['a', null]

Submit your case with the following :

• Function signature
• Function call
• Expected return type

Not sure if you're interested in use-cases, but for your third scenario:

• My function needs a Type that cannot be inferred from the function parameters, hence I need to add a generic type param
• Of one of the function params the type needs to be inferred exactly (Is an Object literal that uses satisfies) for processing and determining the return type based on specific properties in the Object. As such, I need to both store it as a type parameter, but cannot give it a default, leaving me only the option of additional code as the callsite: myFn<firstType, typeof paramValue>(paramValue)

I think your = infer suggestion would solve my challenge, but I wonder if TS could not support it out of the box without any new syntax, by allowing type parameters from not being specified at the callsite if they are tied to mandatory parameters:
declare function myFn<one, two, true = Object>(a: two, b?: three);
myFn(someValueFromWhichToInferTwo);