Add rudimentary display mode capability

src/ValidatedNumerics.jl

@@ -78,6 +78,8 @@ include("misc.jl")
 include("intervals/intervals.jl")
 include("multidim/multidim.jl")
 
+include("display.jl")
+
 include("root_finding/root_finding.jl")
 
 

src/display.jl

@@ -0,0 +1,63 @@
+type DisplayParameters
+    interval_display::Symbol
+    decorations::Bool
+end
+
+const display_params = DisplayParameters(:standard, false)
+
+
+function display_mode(;decorations=nothing, interval_display=nothing)
+    if interval_display != nothing
+        display_params.interval_display = interval_display
+    end
+
+    if decorations != nothing
+        display_params.decorations = decorations
+    end
+end
+
+
+
+## Output
+
+function representation(a::Interval)
+    if isempty(a)
+        return "∅"
+    end
+
+    interval_display = display_params.interval_display
+
+    local output
+
+    if interval_display == :standard
+        output = "[$(a.lo), $(a.hi)]"
+        output = replace(output, "inf", "∞")
+        output = replace(output, "Inf", "∞")
+
+    elseif interval_display == :reproducible
+        output = "Interval($(a.lo), $(a.hi))"
+
+    elseif interval_display == :midpoint_radius
+        output = "$(mid(a)) ± $(diam(a)/2)"
+    end
+
+    output
+end
+
+function representation(a::Interval{BigFloat})
+    if interval_display == :standard
+        string( invoke(representation, (Interval,), a),
+                    subscriptify(precision(a.lo)) )
+
+    elseif interval_display == :reproducible
+        invoke(representation, (Interval,), a)
+    end
+end
+
+show(io::IO, a::Interval) = print(io, representation(a))
+
+function subscriptify(n::Int)
+    subscript_digits = [c for c in "₀₁₂₃₄₅₆₇₈₉"]
+    dig = reverse(digits(n))
+    join([subscript_digits[i+1] for i in dig])
+end