@@ -1027,7 +1027,7 @@ Note that all of what follows is only concerned with syntactic constructs. It do
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10281028We would like to point out that all of the predicates have an operand which is the ``result'' of the predicate -- a single type variable which is said to be equivalent to a more complex expression. That is $\beta$ in predicates \ref{eq:fieldPred} and \ref{eq:optFieldPred}, and $\gamma$ in predicate \ref{eq:upatePred}.
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1030−The observation we need to make is that \emph{referential transparency}\footnote{\url{https://en.wikipedia.org/wiki/Referential_transparency}} is it natural notion in functional programming languages like Nix, and it is natural to replace variables with their definitions. In some sense the ``results'' of predicates described above can be interpreted as being ``defined'' by the predicate to be ``equal'' to the combination of the other operands, and, as such, can be replaced with their definitions.
1030+The observation we need to make is that \emph{referential transparency}\footnote{\url{https://en.wikipedia.org/wiki/Referential_transparency}} is a natural notion in functional programming languages like Nix, and it is natural to replace variables with their definitions. In some sense the ``results'' of predicates described above can be interpreted as being ``defined'' by the predicate to be ``equal'' to the combination of the other operands, and, as such, can be replaced with their definitions.
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10321032This means that we can syntactically replace \emph{type variables} with a portion of a predicate -- replace the variable with the definition. If we apply this technique to the type~\ref{eq:dotExample} we get the following type:
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