# Theory


The theory section explains the ideas behind metaBuilder. It is a companion to
the manual and not a prerequisite for using the library.

The practical claim is short. A build can be written as typed data, that data
can be read as a program, and the program can be interpreted in more than one
way. The theory chapters make each part of that claim precise.

A builder is a typed description rather than a function. The description becomes
a program over a fixed signature of build-time and runtime operations. Domain
builders refine the description with extra data through ornaments, and a typed
forget map projects them back to the shared shape without losing the program.
Every view is an interpretation of that one program.

- [Builders As Descriptions](/metaBuilder/theory/builders-as-descriptions)
- [Internalized Programs](/metaBuilder/theory/internalized-programs)
- [Ornaments And Domain Surfaces](/metaBuilder/theory/ornaments-and-domain-surfaces)
- [Interpretation And Views](/metaBuilder/theory/interpretation-and-views)
- [Evidence, Descriptors, And Runtime Structure](/metaBuilder/theory/evidence-descriptors-runtime)

Read this section when you want to understand why metaBuilder can support one
build with many views.