5 Symbol utilities

(require (planet untyped/unlib/symbol))

Useful symbol utilities.

(symbol+false? item) → boolean?

item : any

Returns #t if item is a symbol or #scheme[#f].

(gensym/interned [base]) → symbol?

base : (U symbol? string?) = "g"

Like gensym but returns an interned symbol that can be compared with other symbols using eq?.

Examples:

> (define sym1 (gensym))

> sym1

g404

> (eq? sym1 (string->symbol (symbol->string sym1)))

#f

> (define sym2 (gensym/interned))

> sym2

g405

> (eq? sym2 (string->symbol (symbol->string sym2)))

#t

(symbol-append sym ...) → symbol?

sym : symbol?

The symbol equivalent of string-append. Returns an interned symbol.

Examples:

> (symbol-append 'abc 'def 'ghi)

abcdefghi

> (symbol-append 'abc)

abc

> (symbol-append)

||

(symbol-length sym) → natural?

sym : symbol?

The symbol equivalent of string-length.

Examples:

> (symbol-length 'AbC123)

6

(symbol-upcase sym) → symbol?

sym : symbol?

The symbol equivalent of string-upcase. Returns an interned symbol.

Examples:

> (symbol-upcase 'AbC123)

ABC123

(symbol-downcase sym) → symbol?

sym : symbol?

The symbol equivalent of string-downcase. Returns an interned symbol.

Examples:

> (symbol-downcase 'AbC123)

abc123

(number->symbol num) → symbol?

num : number?

The symbol equivalent of number->string. Returns an interned symbol.

Examples:

> (number->symbol 123)

|123|

> (number->symbol (/ 1 3))

|1/3|

(symbol->number sym) → number?

sym : symbol?

The symbol equivalent of string->number. Returns #f if sym has no numeric equivalent.

Examples:

> (symbol->number '|123|)

123

> (symbol->number 'abc)

#f

(number+false->symbol+false num) → (U symbol? #f)

num : (U number? #f)

A version of number->symbol that accepts and passes through #f.

(symbol+false->number+false sym) → (U number? #f)

sym : (U symbol? #f)

A version of symbol->number that accepts and passes through #f.

(string+false->symbol+false str) → (U symbol? #f)

str : (U string? #f)

A version of string->symbol that accepts and passes through #f.

(symbol+false->string+false sym) → (U string? #f)

sym : (U symbol? #f)

A version of symbol->string that accepts and passes through #f.