confusing wording of "tail position" description

[edegeltje]

Describe the error

The wording describing what "tail position" means is confusing.

Quote

An expression is in tail position in the function body if it is:

• the function body itself,

• the branches of a match expression that is in tail position,

• the branches of an if expression that is in tail position, and

• the body of a let expression that is in tail position.

Why is it incorrect and/or confusing?

The wording starts out as "an expression is in tail position if it has one of the following properties", resulting in a disjunctive enumeration, while it ends in a conjunctive enumeration (as evidenced by the word "and" as well as the use of plural.)

I would suggest one of the following options:

option 1 (disjunctive list of conditions)

An expression is in tail position in the function body if it is:

• the function body itself,

• a branch of a match expression that is in tail position,

• a branch of an if expression that is in tail position, or

• the body of a let expression that is in tail position.

option 2 (conjunctive list of all options)

The following kinds of expression are in tail position:

• the function body itself,

• the branches of a match expression that is in tail position,

• the branches of an if expression that is in tail position, and

• the body of a let expression that is in tail position.

note that with option 2, "in the function body" is removed from the header of the list. I couldn't find a nice wording that keeps that bit, but as a result i'm not sure that the meaning is as clear and/or still correct. If i am the person writing the PR for this, i will want a second opinion (other than myself), as i am not a native speaker.

[david-christiansen]

Thank you, this is very helpful! I'm knee-deep in the coercion chapter but will resolve this soon.