20 Number utilities

(require (planet untyped/unlib/number))

Useful number utilities.

(number+false? item) → boolean?

item : any

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

(integer+false? item) → boolean?

item : any

Returns #t if item is an integer or #scheme[#f].

(natural? item) → boolean?

item : any

Returns #t if item is an natural number (>= 0).

(natural+false? item) → boolean?

item : any

Returns #t if item is an natural number (>= 0) or #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.

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

num : (U number? #f)

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

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

str : (U string? #f)

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