Introduce 'f' sigils for string interpolation #9512
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This commit introduces a strict way of generating payloads using the `f`
sigils. It constructs a binary and only accepts binaries as dynamic
values. For example:
```erlang
1> User = #{name => ~"Bob", age => 27}.
2> ~f"""
Name: {maps:get(name, User)}
Age: {integer_to_binary(maps:get(age, User))}
""".
<<"Name: Bob\nAgen: 27">>
```
This commit adds more flexibility to the `f` sigil by introducing more
sigil prefixes that output strings. For example:
```erlang
1> User = #{name => ~"Bob", age => 27}.
2> ~fs"""
Name: {maps:get(name, User)}
Age: {integer_to_binary(maps:get(age, User))}
""".
["Name: ",<<"Bob">>,"\nAge: ",<<"27">>]
```
The `f` sigil will not raise an exception for string modifiers if the
dynamic value is not a string or a binary. For example:
```erlang
1> User = #{name => 'Bob', age => 27}.
2> ~fs"""
Name: {maps:get(name, User)}
Age: {maps:get(age, User)}
""".
["Name: ",'Bob',"\nAge: ",27]
```
This commit changes texts to be UTF-8 binaries instead of lists. For example:
```erlang
1> User = #{name => ~"Bob", age => 27}.
2> ~fs"""
Name: {maps:get(name, User)}
Age: {integer_to_binary(maps:get(age, User))}
""".
[<<"Name: ">>,<<"Bob">>,<<"\nAge: ">>,<<"27">>]
```
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williamthome
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It's not easy to determine the exact column of the forms. This commit changes to only store the line as the location to avoid confusion and misleadings. This commit also removes the unneeded text in the strings anno.
|
I have been pondering this for a while, and while I can't really put my finger on it, I have a bad feeling about string interpolation and bringing it in the language 🤷♂️ |
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This PR introduces
~fsigils for ergonomic string interpolation, enabling cleaner binary/iolist generation while reducing boilerplate and errors.Key Features
~f: Returns a flattened binary (ideal for in-memory processing).fs: Returns an iolist (ideal for I/O operations).Note
Currently, Erlang has those sigils:
s,S,b, andB. Following up on all of them, I've also implemented:fb,fB,bforBf: is the same asf.fS,sforSf: is the same asfs.Syntax
{}within the string.{with a backslash\to treat it as a literal.Minimal Example
Why This Is a Good Thing
Developer Experience
<<...>>/++juggling.Flexibility
~f) or iolists (~fs) based on use case.Backward-Compatible
Examples
HTML Templating (
~ffor Binaries)Logging (
~fsfor IOList Efficiency)Edge Cases
Escaping: Use
\{for literal{.Nesting: Combine
~fand~fsfreely.Discussion
No major drawbacks come to mind with this approach, but feedback is welcome.
It would be fantastic to include this feature in OTP-28!
Please see the Erlang Forums thread for more details and discussion.
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