std/misc/string: str

[thibran]

Handy Clojure like procedure that converts a single thing into a string or appends multiple string into one.

> (str 1.0)
"1.0"

> (str "foo" "bar")
"foobar"

I tried to get the output as human friendly as possible by e.g. converting numbers from 2. to 2.0.

[fare]

What are the proposed use cases, compared to repr?

My proposed use cases are for constructing identifiers, etc., in which case I basically want to throw away all the structure, and concatenate the strings, symbols and numbers, without spaces.

(def (str . x) (str1 x))
(def (str1 x (port #f)) (if port (str2 x port) (call-with-output-string (cut str2 x <>))))
(def (str2 x port)
   (cond
    ((or (string? x) (symbol? x) (number? x) (keyword? x) (char? x)) (display x port))
    ((pair? x) (str2 (car x) port) (str2 (cdr x) port))
    ((vector? x) (vector-for-each (cut str2 <> port) x))
    ((member x `(() #f #t #!void #!eof)) (void))
    ((procedure? x) (x port))
    ((displayable? x) => (lambda (m) (m x port)))
    (else (display x port))))

(def (displayable? x)
  (and (object? x) (find-method (object-type x) ':display)))

[vyzo]

LGTM

[thibran]

@fare str It allows someone to convert a thing to a "human friendly" string without thinking much about it.

[vyzo]

This is good to merge imo.

[thibran]

When I started this PR in never thought it would take sooo long.

[vyzo]

One of those things :)

[fare]

Frankly, this thing is enough of its own thing that I would move it out of std/misc/string into its own module.

[thibran]

@fare What would be the benefit to move it out of misc/string? As user I would have to type more (one more import) and as its own module I don't see much growth potentials, what else could be str like and could be added there? Clojure has str in core. But you are right that str is its own little snowflake.

@vyzo Would it be a good idea to check if all values are strings and just call string-concatenate and thereby skipping call-with-output-string when possible?

[vyzo]

Maybe, but how often do we pass a bunch of strings? We can string-append in that case.

[thibran]

@vyzo If someone just wants to get the job done he can go with str. From a use perspective str can "replace" string-append string-concatenate append-strings and handling custom format strings for basic use cases. It's like saying: "just give me a string for x". Very simple, but not as efficient as the other more specialized options.

[vyzo]

ok, let's make it more efficient then.

[vyzo]

ok, I am going to merge it.