Greatly expand docs

Author: MilesCranmer

docs/src/api.md

@@ -17,6 +17,8 @@ ustrip
 dimension
 ```
 
+### Accessing dimensions
+
 Utility functions to extract specific dimensions are as follows:
 
 ```@docs
@@ -44,6 +46,8 @@ The two main functions for working with units are `uparse` and `u_str`:
 uparse
 ```
 
+### Available units
+
 The base SI units are as follows.
 Instead of calling directly, it is recommended to access them via
 the `@u_str` macro, which evaluates the expression

src/types.jl

@@ -19,6 +19,15 @@ which is by default a rational number.
 - `temperature`: temperature dimension (i.e., K^(temperature))
 - `luminosity`: luminosity dimension (i.e., cd^(luminosity))
 - `amount`: amount dimension (i.e., mol^(amount))
+
+# Constructors
+
+- `Dimensions(args...)`: Pass all the dimensions as arguments. `R` is set to `DEFAULT_DIM_TYPE`.
+- `Dimensions(; kws...)`: Pass a subset of dimensions as keyword arguments. `R` is set to `DEFAULT_DIM_TYPE`.
+- `Dimensions(::Type{R}; kws...)` or `Dimensions{R}(; kws...)`: Pass a subset of dimensions as keyword arguments, with the output type set to `Dimensions{R}`.
+- `Dimensions{R}(args...)`: Pass all the dimensions as arguments, with the output type set to `Dimensions{R}`.
+- `Dimensions{R}(d::Dimensions)`: Copy the dimensions from another `Dimensions` object, with the output type set to `Dimensions{R}`.
+
 """
 struct Dimensions{R <: Real}
     length::R
@@ -68,12 +77,21 @@ You can access specific dimensions with `ulength(q)`, `umass(q)`, `utime(q)`,
 `ucurrent(q)`, `utemperature(q)`, `uluminosity(q)`, and `uamount(q)`.
 
 Severals operators in `Base` are extended to work with `Quantity` objects,
-including `*`, `+`, `-`, `/`, `^`, `sqrt`, and `cbrt`.
+including `*`, `+`, `-`, `/`, `abs`, `^`, `sqrt`, and `cbrt`, which manipulate
+dimensions according to the operation.
 
 # Fields
 
-- `value::T`: value of the quantity of some type `T`
-- `dimensions::Dimensions`: dimensions of the quantity
+- `value::T`: value of the quantity of some type `T`. Access with `ustrip(::Quantity)`
+- `dimensions::Dimensions{R}`: dimensions of the quantity with dimension type `R`. Access with `dimension(::Quantity)`
+
+# Constructors
+
+- `Quantity(x; kws...)`: Construct a quantity with value `x` and dimensions given by the keyword arguments. The value type is inferred from `x`. `R` is set to `DEFAULT_DIM_TYPE`.
+- `Quantity(x, ::Type{R}; kws...)`: Construct a quantity with value `x`. The dimensions parametric type is set to `R`.
+- `Quantity(x, d::Dimensions{R})`: Construct a quantity with value `x` and dimensions `d`.
+- `Quantity{T}(q::Quantity)`: Construct a quantity with value `q.value` and dimensions `q.dimensions`, but with value type converted to `T`.
+- `Quantity{T,R}(q::Quantity)`: Construct a quantity with value `q.value` and dimensions `q.dimensions`, but with value type converted to `T` and dimensions parametric type set to `R`.
 """
 struct Quantity{T, R}
     value::T