1. I'm not an expert in nim-decimal, but apparently it's the default way. But
you can always make a 'round' procedure (by wrapping 'quantize') if you're more
comfortable with it.
2. It can't be pure because +, - , etc.. operators defined by nim-decimal
rely on global decimal context (`Hint: '+' accesses global state 'CTX_ADDR'`).
For procedure to be pure - all procedures inside of it should also be pure.
3. you can create your custom types which would work as an alias for other
types, and you can use a single type with multiple procedure arguments to
reduce typing:
type Dec = DecimalType
proc wacc(e, d, rE, rD, t: Dec ): Dec =
Run
3.5 you can use a single let, var, const, type.. instead of multiple:
let
a = 1
b = 2
Run
4. brilliantly answered by ElegantBeef
If we combine all of techniques, we will get very idiomatic Nim code:
type Dec = DecimalType
template `'dec`(s: string | SomeInteger): DecimalType = newDecimal(s)
proc wacc(e, d, rE, rD, t: Dec ): Dec =
let
v = e + d
eV = e / v
dV = d / v
adjRD = rD * (1 - t)
eV * rE + dV * adjRD
let
e = 1000000'dec
d = 2000000'dec
rE = 0.15'dec
rD = 0.05'dec
t = 0.3'dec
let w = wacc(e, d, rE, rD, t)
let y = quantize(w, newDecimal("1e-3"))
echo reduce(y * 100), '%'
Run
