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52.2 Escape sequences for generic values

Format Escape Sequence: ~a
Format Escape Sequence: ~s

Object output. Parameters: minwidth, padinc, minpad, padchar.

~a outputs an argument like display, ~s outputs an argument like write. 

(format #t "~a" "foo") -| foo
(format #t "~s" "foo") -| "foo"

~:a and ~:s put objects that don’t have an external representation in quotes like a string. 

(format #t "~:a" car) -| "#<primitive-procedure car>"

If the output is less than minwidth characters (default 0), it’s padded on the right with padchar (default space). ~@a and ~@s put the padding on the left instead. 

(format #f "~5a" 'abc)       ⇒ "abc  "
(format #f "~5,,,'-@a" 'abc) ⇒ "--abc"

The number of padding characters, padchar, included in the output is computed with: minpad + N * padinc, where n is the smallest integer making the total object plus padding greater than or equal to minwidth. The default minpad is 0 and the default padinc is 1 (imposing no minimum or multiple). 

(format #f "~5,1,4a" 'abc) ⇒ "abc    "

More examples: 

(import (except (vicare) format)
  (vicare formations))

(format #f "ciao ~:a" display)
⇒ "ciao \"#<procedure display>\""

(format "~5a" 123)              ⇒ "123  "
(format "~5s" 123)              ⇒ "123  "

(format "~5@a" 123)            ⇒ "  123"
(format "~5@s" 123)            ⇒ "  123"

(format "~5,,,'.a" 123)         ⇒ "123.."
(format "~5,,,'.s" 123)         ⇒ "123.."

(format "~5,,,'.@a" 123)       ⇒ "..123"
(format "~5,,,'.@s" 123)       ⇒ "..123"

(format "~5,,4,'.@a" 123)      ⇒ "....123"
(format "~5,,4,'.@s" 123)      ⇒ "....123"
;;;                                1234

(format "~10,,,'a@a" 123)      ⇒ "aaaaaaa123"
(format "~10,,,'a@s" 123)      ⇒ "aaaaaaa123"
;;;                                1234567

(format "~10,3,,'u@a" 123)     ⇒ "uuuuuuuuu123"
(format "~10,3,,'u@s" 123)     ⇒ "uuuuuuuuu123"
;;;                                123456789

(format "~11,2,,'u@a" 123)     ⇒ "uuuuuuuu123"
(format "~11,2,,'u@s" 123)     ⇒ "uuuuuuuu123"
;;;                                12345678

(format "~8,2,,'u@a" 1)        ⇒ "uuuuuuuu1"
(format "~8,2,,'u@s" 1)        ⇒ "uuuuuuuu1"
;;;                                12345678

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