26 Syntax utilities

(require (planet untyped/unlib/syntax))

Utilities for creating macros and working with syntax.

(symbolic-identifier=? stx1 stx2) → boolean?

stx1 : syntax?

stx2 : syntax?

Compares two identifiers based on their symbolic representation.

(make-id stx arg ...) → syntax?

stx : (U syntax? #f)

arg : (U syntax? string? symbol? number?)

Creates an identifier by appending args. Equivalent to:

  (datum->syntax stx (string->symbol (apply string-append (map arg->string args))))

where arg->string converts an argument to a string.

(syntax-location-string stx) → string?

stx : syntax?

Returns a string describing the source location of stx (for example "myfile.ss:123:45").

(begin-for-syntax/any-order definition ...)

definition   =   (define (id arg ...) expr ...)     |   (define id expr)

Like begin-for-syntax except that definitions can refer to previous definitions in the manner of a letrec statement. Only definitions are allowed within the body of the form.

(dotted-identifier? stx [min-parts max-parts]) → boolean?

stx : syntax?

min-parts : (U natural? #f) = 2

max-parts : (U natural? #f) = #f

Returns #f if stx represents an identifier comprised of one or more parts joined by dots. Parts can be zero-length.

The min-parts and max-parts arguments can be used limit the number of allowed parts (both limits are inclusive).

Examples:

> (dotted-identifier? #'a)

#f

> (dotted-identifier? #'.a)

#t

> (dotted-identifier? #'a.b)

#t

> (dotted-identifier? #'a.)

#t

> (dotted-identifier? #'a.b.c 3 3)

#t

> (dotted-identifier? #'a 1)

#t

(simple-dotted-identifier?   stx            [ min-parts             max-parts])   →   boolean?

stx : syntax?

min-parts : (U natural? #f) = 2

max-parts : (U natural? #f) = #f

Like dotted-identifier? except all parts must be a minimum length of 1.

Examples:

> (simple-dotted-identifier? #'a)

#f

> (simple-dotted-identifier? #'a.b)

#t

> (simple-dotted-identifier? #'.a)

#f

> (simple-dotted-identifier? #'a.)

#f

(dotted-identifier-count dotted-id-stx) → natural?

dotted-id-stx : identifier?

Returns the number of parts in dotted-id-stx.

Examples:
> (dotted-identifier-count #'a)
1
> (dotted-identifier-count #'a.b)
2
> (dotted-identifier-count #'a.b.c)
3
> (dotted-identifier-count #'.a)
2

(dotted-identifier-split dotted-id-stx) → (listof identifier?)

dotted-id-stx : identifier?

Splits dotted-id-stx into its constituent parts.

Examples:

> (map syntax->datum (dotted-identifier-split #'a))

(a)

> (map syntax->datum (dotted-identifier-split #'a.b))

(a b)

> (map syntax->datum (dotted-identifier-split #'a.b.c))

(a b c)

> (map syntax->datum (dotted-identifier-split #'.a))

(|| a)