humane

Human-readable file sizes (1000-based math, capitalized labels, the way Mac Finder displays them) and relative times ("3 minutes ago", "in 3 hours") for Go and Ruby HTML templates -- as simple to drop in as ActionView's own helpers, with output that's consistent with humane-ruby and humane-swift.

import "github.com/woodie/humane"

humane.HumanSize(225935) // "226 KB"

mtime := time.Now().Add(-180 * time.Second)
humane.TimeAgo(mtime) // "3 minutes ago" -- relative to the real clock

now := time.Now()
humane.DistanceInTime(&mtime, now) // "3 minutes ago" -- explicit relativeTo, for tests

go get github.com/woodie/humane

Two entry points, same naming split as ActionView's own distance_of_time_in_words/time_ago_in_words:

• DistanceInTime(at *time.Time, relativeTo, ...) -- the explicit, fully-tested core. Takes both times, plus a possibly-nil at, so it's what tests should call.
• TimeAgo(at time.Time, ...) -- a one-argument convenience for the common "drop into a view" case, where a timestamp is always in hand. Supplies time.Now() as relativeTo internally.

Both share the same options and recommended defaults, already matching ActionView's own distance_of_time_in_words defaults -- pass none at all and you get them for free:

humane.DistanceInTime(at, relativeTo) // Approximate: true, IncludeSeconds: false
humane.TimeAgo(at)                    // same defaults, relativeTo is time.Now()

• Approximate (*bool, default true): prefixes "about"/"in about" on the hour-scale buckets (1 hour, and 2..24 hours), matching ActionView's distance_of_time_in_words wording for those buckets exactly (down to its 44:30/89:30 rounding cutoffs), through the "1 day" bucket. This is a *bool, not a bool -- see "Why Approximate is a pointer" below.
• IncludeSeconds (bool, default false): under 30 seconds, collapses to "less than a minute ago"/"in less than a minute" instead of an exact second count. Matches ActionView's include_seconds default.
• WhenNil (string, default ""): if at is nil, DistanceInTime returns this string without formatting -- for a scan, download, or other record that doesn't have a timestamp yet. TimeAgo takes at by value (never nil); use DistanceInTime directly for a possibly-missing timestamp.

humane.DistanceInTime(at, relativeTo, humane.TimeOptions{Approximate: humane.Bool(false)})
// "15 hours ago", not "about 15 hours ago"

humane.DistanceInTime(nil, time.Now(), humane.TimeOptions{WhenNil: "an unknown time"})
// "an unknown time"

TimeOptions{}'s zero value needs to mean "use the recommended defaults," and Go can't default a bare bool field to true from a struct literal -- the zero value of bool is always false. (This is the same footgun that IncludeSeconds used to have under its old name, CollapseMinute; see docs/COMMENTS.md.) Rather than silently defaulting Approximate to false whenever you write an explicit TimeOptions{...} for some other field, Approximate is a *bool: nil means "use the default (true)", and humane.Bool(false) opts out.

Finder's byte-count style, and a numeric (non-calendar-aware) relative time style through the "1 day" bucket -- that's the whole surface area today. Alternate size units/styles and a .named style ("yesterday", calendar-boundary-aware) aren't implemented -- contributions welcome.

golangci-lint run
go test -v ./... | gorderly -fd

or, if you don't have gorderly installed:

go vet ./...
go test ./...