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Diffstat (limited to 'doc/manual.tex')
| -rw-r--r-- | doc/manual.tex | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/doc/manual.tex b/doc/manual.tex index 6cbecea3..84b300e7 100644 --- a/doc/manual.tex +++ b/doc/manual.tex @@ -517,7 +517,7 @@ $$\begin{array}{rrcll} &&& \mt{constraint} \; c \sim c & \textrm{record disjointness constraint} \\ &&& \mt{open} \; \mt{constraints} \; M & \textrm{inclusion of just the constraints from a module} \\ &&& \mt{table} \; x : c & \textrm{SQL table} \\ - &&& \mt{view} \; x : c & \textrm{SQL view} \\ + &&& \mt{view} \; x = e & \textrm{SQL view} \\ &&& \mt{sequence} \; x & \textrm{SQL sequence} \\ &&& \mt{cookie} \; x : \tau & \textrm{HTTP cookie} \\ &&& \mt{style} \; x : \tau & \textrm{CSS class} \\ @@ -533,7 +533,7 @@ $$\begin{array}{rrcll} There are two kinds of Ur files. A file named $M\texttt{.ur}$ is an \emph{implementation file}, and it should contain a sequence of declarations $d^*$. A file named $M\texttt{.urs}$ is an \emph{interface file}; it must always have a matching $M\texttt{.ur}$ and should contain a sequence of signature items $s^*$. When both files are present, the overall effect is the same as a monolithic declaration $\mt{structure} \; M : \mt{sig} \; s^* \; \mt{end} = \mt{struct} \; d^* \; \mt{end}$. When no interface file is included, the overall effect is similar, with a signature for module $M$ being inferred rather than just checked against an interface. -We omit some extra possibilities in $\mt{table}$ syntax, deferring them to Section \ref{tables}. +We omit some extra possibilities in $\mt{table}$ syntax, deferring them to Section \ref{tables}. The concrete syntax of $\mt{view}$ declarations is also more complex than shown in the table above, with details deferred to Section \ref{tables}. \subsection{Shorthands} @@ -985,8 +985,8 @@ $$\infer{\Gamma \vdash \mt{constraint} \; c_1 \sim c_2 \leadsto \Gamma}{ $$\infer{\Gamma \vdash \mt{table} \; x : c \leadsto \Gamma, x : \mt{Basis}.\mt{sql\_table} \; c \; []}{ \Gamma \vdash c :: \{\mt{Type}\} } -\quad \infer{\Gamma \vdash \mt{view} \; x : c \leadsto \Gamma, x : \mt{Basis}.\mt{sql\_view} \; c}{ - \Gamma \vdash c :: \{\mt{Type}\} +\quad \infer{\Gamma \vdash \mt{view} \; x = e \leadsto \Gamma, x : \mt{Basis}.\mt{sql\_view} \; c}{ + \Gamma \vdash e :: \mt{Basis}.\mt{sql\_query} \; [] \; [] \; (\mt{map} \; (\lambda \_ \Rightarrow []) \; c') \; c }$$ $$\infer{\Gamma \vdash \mt{sequence} \; x \leadsto \Gamma, x : \mt{Basis}.\mt{sql\_sequence}}{}$$ @@ -1221,7 +1221,7 @@ $$\infer{\Gamma \vdash M_1(M_2) : [X \mapsto M_2]S_2}{ \mt{sigOf}(\mt{constraint} \; c_1 \sim c_2) &=& \mt{constraint} \; c_1 \sim c_2 \\ \mt{sigOf}(\mt{open} \; \mt{constraints} \; M) &=& \cdot \\ \mt{sigOf}(\mt{table} \; x : c) &=& \mt{table} \; x : c \\ - \mt{sigOf}(\mt{view} \; x : c) &=& \mt{view} \; x : c \\ + \mt{sigOf}(\mt{view} \; x = e) &=& \mt{view} \; x : c \textrm{ (where $\Gamma \vdash e : \mt{Basis}.\mt{sql\_query} \; [] \; [] \; (\mt{map} \; (\lambda \_ \Rightarrow []) \; c') \; c$)} \\ \mt{sigOf}(\mt{sequence} \; x) &=& \mt{sequence} \; x \\ \mt{sigOf}(\mt{cookie} \; x : \tau) &=& \mt{cookie} \; x : \tau \\ \mt{sigOf}(\mt{style} \; x) &=& \mt{style} \; x \\ @@ -2088,14 +2088,15 @@ Ur/Web features some syntactic shorthands for building values using the function $\mt{table}$ declarations may include constraints, via these grammar rules. $$\begin{array}{rrcll} - \textrm{Declarations} & d &::=& \mt{table} \; x : c \; [pk[,]] \; cts \\ + \textrm{Declarations} & d &::=& \mt{table} \; x : c \; [pk[,]] \; cts \mid \mt{view} \; x = V \\ \textrm{Primary key constraints} & pk &::=& \mt{PRIMARY} \; \mt{KEY} \; K \\ \textrm{Keys} & K &::=& f \mid (f, (f,)^+) \\ \textrm{Constraint sets} & cts &::=& \mt{CONSTRAINT} f \; ct \mid cts, cts \mid \{\{e\}\} \\ \textrm{Constraints} & ct &::=& \mt{UNIQUE} \; K \mid \mt{CHECK} \; E \\ &&& \mid \mt{FOREIGN} \; \mt{KEY} \; K \; \mt{REFERENCES} \; F \; (K) \; [\mt{ON} \; \mt{DELETE} \; pr] \; [\mt{ON} \; \mt{UPDATE} \; pr] \\ \textrm{Foreign tables} & F &::=& x \mid \{\{e\}\} \\ - \textrm{Propagation modes} & pr &::=& \mt{NO} \; \mt{ACTION} \mid \mt{RESTRICT} \mid \mt{CASCADE} \mid \mt{SET} \; \mt{NULL} + \textrm{Propagation modes} & pr &::=& \mt{NO} \; \mt{ACTION} \mid \mt{RESTRICT} \mid \mt{CASCADE} \mid \mt{SET} \; \mt{NULL} \\ + \textrm{View expressions} & V &::=& Q \mid \{e\} \end{array}$$ A signature item $\mt{table} \; \mt{x} : \mt{c}$ is actually elaborated into two signature items: $\mt{con} \; \mt{x\_hidden\_constraints} :: \{\{\mt{Unit}\}\}$ and $\mt{val} \; \mt{x} : \mt{sql\_table} \; \mt{c} \; \mt{x\_hidden\_constraints}$. This is appropriate for common cases where client code doesn't care which keys a table has. It's also possible to include constraints after a $\mt{table}$ signature item, with the same syntax as for $\mt{table}$ declarations. This may look like dependent typing, but it's just a convenience. The constraints are type-checked to determine a constructor $u$ to include in $\mt{val} \; \mt{x} : \mt{sql\_table} \; \mt{c} \; (u \rc \mt{x\_hidden\_constraints})$, and then the expressions are thrown away. Nonetheless, it can be useful for documentation purposes to include table constraint details in signatures. Note that the automatic generation of $\mt{x\_hidden\_constraints}$ leads to a kind of free subtyping with respect to which constraints are defined. |