compile/bare-syntax

Symbol: compile/bare-syntax

Syntax: (bare-syntax NAME SLOT TEMPLATE)

Use-case: A bare arm for a transformer – the expansion used when the syntax name appears as a lone atom instead of at the head of a call form. (counter 4) reaches the call arms; a bare counter reaches the bare arm.

Behaviour: SLOT names the called-by capture, and is the only binding TEMPLATE may refer to; it holds the symbol as written at the use site. The form lowers to a Syntax carrying only that arm. Bind it with syntax to make a syntax that has no call arms, or attach it to an existing syntax with extend-syntax.

Block syntax: bare-syntax SLOT: with the template as the body, or bare-syntax NAME SLOT: with a leading name. A multi-form body is wrapped in begin. See layout/bare-syntax.

Examples:

>>> syntax greeting:
...   bare-syntax slot:
...     "hello"
>>> greeting
"hello"

A bare arm added to an existing transformer:

>>> syntax counter:
...   syntax-rules []:
...     case (counter n):
...       (+ n 1)
>>> extend-syntax counter:
...   bare-syntax slot:
...     0
>>> counter
0
>>> (counter 4)
5

The slot carries the name as written:

>>> syntax whoami:
...   bare-syntax me:
...     (str (quote me))
>>> whoami
"whoami"

Also: layout handler bare-syntax.