Ghost.jl

Ghost.jl is a code tracer for the Julia programming language. It lets you trace the function execution, recording all primitive operations onto a linearized tape. Here's a quick example:

inc(x) = x + 1
mul(x, y) = x * y
inc_double(x) = mul(inc(x), inc(x))

val, tape = trace(inc_double, 2.0)

(9.0, Tape{Dict{Any, Any}}
  inp %1::typeof(Main.inc_double)
  inp %2::Float64
  %3 = +(%2, 1)::Float64
  %4 = +(%2, 1)::Float64
  %5 = *(%3, %4)::Float64
)

The tape can then be analyzed, modified and even compiled back to a normal function. See the following sections for details.