A new formatting library that tries to be simple to understand while still
being powerful and providing more convenience features than other libraries
(like functions for pretty-printing maps and lists, or a function for
printing arbitrary datatypes using generics).
A comparison with other libraries:
printf (from Text.Printf) takes a formatting string and uses some
type tricks to accept the rest of the arguments polyvariadically. It's
very concise, but there are some drawbacks – it can't produce Text
(you'd have to T.pack it every time) and it doesn't warn you at
compile-time if you pass wrong arguments or not enough of them.
text-format takes a
formatting string with angle brackets denoting places where arguments
would be substituted (the arguments themselves are provided via a
tuple). If you want to apply formatting to some of the arguments, you
have to use one of the provided formatters. Like printf, it can fail at
runtime, but at least the formatters are first-class (and you can add new
ones).
formatting takes a
formatting template consisting of pieces of strings interleaved with
formatters; this ensures that arguments always match their placeholders.
formatting provides lots of formatters and generally seems to be the
most popular formatting library here. Unfortunately, at least in my
experience writing new formatters can be awkward and people sometimes
have troubles understanding how formatting works.
fmt (i.e. this library)
provides formatters that are ordinary functions, and a bunch of operators
for concatenating formatted strings; those operators also do automatic
conversion. There are some convenience formatters which aren't present in
formatting (like ones for formatting maps, lists, converting to base64,
etc). Some find the operator syntax annoying, while others like it.
Changes
0.3.0.0
Added time formatters (see Fmt.Time).
0.2.0.0
Changed format and formatLn to be polyvariadic.
0.1.0.0
Added genericF for formatting arbitrary data.
Changed %< and >% to #| and |# because they turn out to be easier to type.
Added a migration guide from formatting.
Changed output of eitherF.
Added bechmarks.
0.0.0.4
Added format from text-format, because in some cases it’s nicer than brackets.
Renamed padCenterF to padBothF.
Modified indent and indent' to always add newlines.
0.0.0.3
Wrote documentation.
Added some formatters:
indent
formatters for lists, maps and tuples (listF, etc)
octF, binF, baseF and floating-point formatters
hexF which works on both numbers and bytestrings
ordinalF and commaizeF
padding and trimming formatters
base64F and base64UrlF
conditionals (whenF and unlessF)
Merged Fmt.IO with Fmt because orphan instances are controversial.
Exported internal classes and functions from Fmt.Internal.
Added fmt and fmtLn.
Made all operators associate to the right (Builder documentation says it’s faster than the opposite).
Reexported Buildable and Builder.
0.0.0.2
Added >%%< so that it’d be possible to write %<a>%%<b>% instead of weird %<a%<b>%.
Added %<< ... >>%, which work work Show instead of Buildable. If you don’t care about speed and just want to output something, use them.
Added an IO () instance in Fmt.IO. If you import that module, raw formatted strings would print themselves.
Added tests.
Changed fixities of operators so that %<n+1>% would work.
Changed license to BSD3 since all our dependencies are BSD3 and we can’t use MIT.