TermColor.Detect: conservative terminal selection and output

Detection follows common command-line conventions: NO_COLOR wins over FORCE_COLOR and disables colors while retaining text attributes on a TTY, a non-empty FORCE_COLOR enables ANSI output even when stdout is redirected, and TERM=dumb disables all styling. This is policy, not part of the pure rendering model, so callers can always pass an explicit RenderTarget instead.

inductive TermColor.ColorChoice : Type

Policy for choosing whether to emit terminal colors.

• auto : ColorChoice

  Detect the environment and TTY status.

• always : ColorChoice

  Force styled output when supported.

• never : ColorChoice

  Force plain output.

@[instance_reducible]

instance TermColor.instBEqColorChoice : BEq ColorChoice

Equations

• TermColor.instBEqColorChoice = { beq := TermColor.instBEqColorChoice.beq }

def TermColor.instBEqColorChoice.beq : ColorChoice → ColorChoice → Bool

Equations

• TermColor.instBEqColorChoice.beq x✝ y✝ = (x✝.ctorIdx == y✝.ctorIdx)

@[instance_reducible]

instance TermColor.instDecidableEqColorChoice : DecidableEq ColorChoice

Equations

• TermColor.instDecidableEqColorChoice x✝ y✝ = if h : x✝.ctorIdx = y✝.ctorIdx then isTrue ⋯ else isFalse ⋯

def TermColor.instReprColorChoice.repr : ColorChoice → Nat → Std.Format

Equations

• One or more equations did not get rendered due to their size.

@[instance_reducible]

instance TermColor.instReprColorChoice : Repr ColorChoice

Equations

• TermColor.instReprColorChoice = { reprPrec := TermColor.instReprColorChoice.repr }

def TermColor.targetWithTty (choice : ColorChoice := ColorChoice.auto) (tty : Bool) : IO RenderTarget

Choose a render target from the environment and a caller-supplied TTY result.

Equations

• One or more equations did not get rendered due to their size.

def TermColor.target (choice : ColorChoice := ColorChoice.auto) : IO RenderTarget

Choose a render target from the current process environment and stdout.

Equations

• TermColor.target choice = do let __do_lift ← liftM IO.getStdout let __do_lift ← liftM __do_lift.isTty TermColor.targetWithTty choice __do_lift

def TermColor.render (text : Text) (choice : ColorChoice := ColorChoice.auto) : IO String

Render text using explicit or automatically detected output policy.

Equations

• TermColor.render text choice = do let __do_lift ← TermColor.target choice pure (TermColor.Text.render __do_lift text)

def TermColor.print (text : Text) (choice : ColorChoice := ColorChoice.auto) : IO Unit

Print text using explicit or automatically detected output policy.

Equations

• TermColor.print text choice = do let __do_lift ← TermColor.render text choice IO.print __do_lift