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Add Str.replaceFirst builtin

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Jan Van Bruggen 2022-09-12 00:42:13 -06:00 • committed by Jan Van Bruggen
parent 15eb36e4ab
commit c5b6aef21a
1 changed files with 12 additions and 0 deletions
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12
crates/compiler/builtins/roc/Str.roc
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@ -33,6 +33,7 @@ interface Str
toU8,
toI8,
toScalars,
replaceFirst,
splitFirst,
splitLast,
walkUtf8WithIndex,
@ -276,6 +277,17 @@ countUtf8Bytes : Str -> Nat
## string slice that does not do bounds checking or utf-8 verification
substringUnsafe : Str, Nat, Nat -> Str
## Returns the string with the first occurrence of a substring replaced with a replacement.
## If the substring is not found, returns `Err NotFound`.
##
## Str.replaceFirst "foo/bar/baz" "/" "_" == Ok "foo_bar/baz"
replaceFirst : Str, Str, Str -> Result Str [NotFound]*
replaceFirst = \haystack, needle, flower ->
when splitFirst haystack needle is
Ok { before, after } ->
"\(before)\(flower)\(after)"
err -> err
## Returns the string before the first occurrence of a delimiter, as well as the
## rest of the string after that occurrence. If the delimiter is not found, returns `Err`.
##