This package makes it easy to change the "default" precision of a large body of Julia code, simply by prefixing it with the @changeprecision T expression macro, for example:

@changeprecision Float32 begin
    x = 7.3
    y = 1/3
    z = rand() .+ ones(3,4)
end

In particular, floating-point literals like 7.3 are reinterpreted as the requested type Float32, operations like / that convert integer arguments to Float64 instead convert to Float32, and random-number or matrix constructors like rand and ones default to Float32 instead of Float64.

Code that explicitly specifies a type, e.g. rand(Float64), is unaffected by @changeprecision.