hanez/fun
1
0
Fork 0
forked from fun/fun
Code Pull requests Activity
fun/web/documentation/strings/strings.md

2.8 KiB
Raw Blame History

layout published noToc noComments noDate title subtitle description permalink lang tags
page true false false false Fun - Working with strings in Fun Working with strings, literals/escaping, concatenation, substr/find, split, and conversions. Working with strings, literals/escaping, concatenation, substr/find, split, and conversions. /documentation/strings/ en
concatenation
conversions
escaping
find
literals
split
strings
substr

This guide covers string literals, common operations (length, concatenation, substring, search, split), and interop patterns. Strings in Fun are immutable sequences of bytes/text.

TL;DR

  • Create with quotes: s = "hello". Escape with \n, \t, ", \.
  • Concatenate with +. Convert non-strings with to_string(x).
  • Length: len(s). Substring: substr(s, start, length).
  • Find index: find(s, needle) → 0-based index or -1 if not found.
  • Split CSV: split("a,b,c", ",") → ["a","b","c"].

Literals and escaping

s1 = "hello"
s2 = "line1\nline2"   // newline
s3 = "quote: \" and backslash: \\" // escaped quote and backslash

print(s1)  // hello

Notes:

  • Strings are immutable; operations return new strings rather than modifying in place.
  • Use to_string(x) when concatenating non-string values.

Basic operations

Length and concatenation:

name = "Ada"
greet = "Hello, " + name + "!"    // "Hello, Ada!"
print(len(greet))                   // 12

Substring (start, length) and search:

s = "hello, world"
print(substr(s, 7, 5))   // world
idx = find(s, ",")      // 5, or -1 if not found
if idx >= 0 { print("comma at index " + to_string(idx)) }

Splitting into arrays:

parts = split("a,b,c", ",")  // ["a","b","c"]
for i = 0; i < len(parts); i = i + 1 {
  print(parts[i])
}

Conversions and formatting

n = 42
pi = 3.14
msg = "n=" + to_string(n) + ", pi=" + to_string(pi)
print(msg)

// parsing (may error if the string is not numeric)
n2 = to_number("123")    // 123

If you need a specific type, you can use cast for advanced cases, e.g. cast("123", "number").

Common patterns

  • Guard on find results before slicing:
email = "user@example.org"
at = find(email, "@")
if at >= 0 {
  user = substr(email, 0, at)
  host = substr(email, at + 1, len(email) - at - 1)
  print(user + " on " + host)
}
  • Building paths or messages:
base = "/tmp"
file = "log.txt"
path = base + "/" + file

Gotchas

  • Strings are immutable: repeated concatenation in big loops can be costly; consider collecting pieces in an array and joining at the end if you have a helper for that in your setup.
  • len(s) counts bytes/code units; be mindful when working with multibyte encodings.

See also