Print a progress bar

Erases the current line! (by outputting '\r') Does not print a newline '\n'. Subsequent invocations will overwrite the previous output.

Remember to set the correct buffering mode for stdout:

 import System.IO ( hSetBuffering, BufferMode(NoBuffering), stdout )
 hSetBuffering stdout NoBuffering

Renders a progress bar

>>> mkProgressBar (msg "Working") percentage 40 30 100
"Working [=======>.................]  30%"

A label that can be pre- or postfixed to a progress bar.

The empty label.

>>> noLabel 30 100
""

A label consisting of a static string.

>>> msg "foo" 30 100
"foo"

A label which displays the progress as a percentage.

Constant width property: ∀ d t : ℕ. d ≤ t → length (percentage d t) ≡ 4

>>> percentage 30 100
" 30%"

A label which displays the progress as a fraction of the total amount of work.

Equal width property: ∀ d₁ d₂ t : ℕ. d₁ ≤ d₂ ≤ t → length (exact d₁ t) ≡ length (exact d₂ t)

>>> exact 30 100
" 30/100"