too many clashes with "root" on reals

added and renamed functions

added an example

clarified ML_Context.expression: it is a closed expression, not a let-declaration -- thus source positions are more accurate (amending d8849cfad60f, 162a4c2e97bc);

tuned;

tuned;

merged

tuned example;

added GHC.read_source: read Haskell source text with antiquotations; added "cartouche" antiquotation for ML string expressions as Haskell string literals;

tuned -- prefer GHC.print_codepoint;