diff options
| -rw-r--r-- | doc/manual.tex | 34 | ||||
| -rw-r--r-- | lib/ur/basis.urs | 4 |
2 files changed, 25 insertions, 13 deletions
diff --git a/doc/manual.tex b/doc/manual.tex index 7a0a0002..fb056fd0 100644 --- a/doc/manual.tex +++ b/doc/manual.tex @@ -1129,14 +1129,27 @@ The Ur compiler treates $\mt{folder}$ like a constructor class, using built-in r \section{The Ur/Web Standard Library} +\subsection{Monads} + +The Ur Basis defines the monad constructor class from Haskell. + +$$\begin{array}{l} + \mt{class} \; \mt{monad} :: \mt{Type} \to \mt{Type} \\ + \mt{val} \; \mt{return} : \mt{m} ::: (\mt{Type} \to \mt{Type}) \to \mt{t} ::: \mt{Type} \\ + \hspace{.1in} \to \mt{monad} \; \mt{m} \\ + \hspace{.1in} \to \mt{t} \to \mt{m} \; \mt{t} \\ + \mt{val} \; \mt{bind} : \mt{m} ::: (\mt{Type} \to \mt{Type}) \to \mt{t1} ::: \mt{Type} \to \mt{t2} ::: \mt{Type} \\ + \hspace{.1in} \to \mt{monad} \; \mt{m} \\ + \hspace{.1in} \to \mt{m} \; \mt{t1} \to (\mt{t1} \to \mt{m} \; \mt{t2}) \\ + \hspace{.1in} \to \mt{m} \; \mt{t2} +\end{array}$$ + \subsection{Transactions} Ur is a pure language; we use Haskell's trick to support controlled side effects. The standard library defines a monad $\mt{transaction}$, meant to stand for actions that may be undone cleanly. By design, no other kinds of actions are supported. $$\begin{array}{l} \mt{con} \; \mt{transaction} :: \mt{Type} \to \mt{Type} \\ - \\ - \mt{val} \; \mt{return} : \mt{t} ::: \mt{Type} \to \mt{t} \to \mt{transaction} \; \mt{t} \\ - \mt{val} \; \mt{bind} : \mt{t_1} ::: \mt{Type} \to \mt{t_2} ::: \mt{Type} \to \mt{transaction} \; \mt{t_1} \to (\mt{t_1} \to \mt{transaction} \; \mt{t_2}) \to \mt{transaction} \; \mt{t_2} + \mt{val} \; \mt{transaction\_monad} : \mt{monad} \; \mt{transaction} \end{array}$$ \subsection{HTTP} @@ -1175,7 +1188,7 @@ $$\begin{array}{l} Queries are used by folding over their results inside transactions. $$\begin{array}{l} \mt{val} \; \mt{query} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{exps} ::: \{\mt{Type}\} \to \lambda [\mt{tables} \sim \mt{exps}] \Rightarrow \mt{state} ::: \mt{Type} \to \mt{sql\_query} \; \mt{tables} \; \mt{exps} \\ - \hspace{.1in} \to (\$(\mt{exps} \rc \mt{fold} \; (\lambda \mt{nm} \; (\mt{fields} :: \{\mt{Type}\}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \$\mt{fields}] \rc \mt{acc}) \; [] \; \mt{tables}) \\ + \hspace{.1in} \to (\$(\mt{exps} \rc \mt{map} \; (\lambda \mt{fields} :: \{\mt{Type}\} \Rightarrow \$\mt{fields}) \; \mt{tables}) \\ \hspace{.2in} \to \mt{state} \to \mt{transaction} \; \mt{state}) \\ \hspace{.1in} \to \mt{state} \to \mt{transaction} \; \mt{state} \end{array}$$ @@ -1203,12 +1216,12 @@ $$\begin{array}{l} \hspace{.1in} \to \mt{grouped} ::: \{\{\mt{Type}\}\} \\ \hspace{.1in} \to \mt{selectedFields} ::: \{\{\mt{Type}\}\} \\ \hspace{.1in} \to \mt{selectedExps} ::: \{\mt{Type}\} \\ - \hspace{.1in} \to \{\mt{From} : \$(\mt{fold} \; (\lambda \mt{nm} \; (\mt{fields} :: \{\mt{Type}\}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{sql\_table} \; \mt{fields}] \rc \mt{acc}) \; [] \; \mt{tables}), \\ + \hspace{.1in} \to \{\mt{From} : \$(\mt{map} \; \mt{sql\_table} \; \mt{tables}), \\ \hspace{.2in} \mt{Where} : \mt{sql\_exp} \; \mt{tables} \; [] \; [] \; \mt{bool}, \\ \hspace{.2in} \mt{GroupBy} : \mt{sql\_subset} \; \mt{tables} \; \mt{grouped}, \\ \hspace{.2in} \mt{Having} : \mt{sql\_exp} \; \mt{grouped} \; \mt{tables} \; [] \; \mt{bool}, \\ \hspace{.2in} \mt{SelectFields} : \mt{sql\_subset} \; \mt{grouped} \; \mt{selectedFields}, \\ - \hspace{.2in} \mt {SelectExps} : \$(\mt{fold} \; (\lambda \mt{nm} \; (\mt{t} :: \mt{Type}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{sql\_exp} \; \mt{grouped} \; \mt{tables} \; [] \; \mt{t}] \rc \mt{acc}) \; [] \; \mt{selectedExps}) \} \\ + \hspace{.2in} \mt {SelectExps} : \$(\mt{map} \; (\mt{sql\_exp} \; \mt{grouped} \; \mt{tables} \; []) \; \mt{selectedExps}) \} \\ \hspace{.1in} \to \mt{sql\_query1} \; \mt{tables} \; \mt{selectedFields} \; \mt{selectedExps} \end{array}$$ @@ -1217,9 +1230,8 @@ $$\begin{array}{l} \mt{con} \; \mt{sql\_subset} :: \{\{\mt{Type}\}\} \to \{\{\mt{Type}\}\} \to \mt{Type} \\ \mt{val} \; \mt{sql\_subset} : \mt{keep\_drop} :: \{(\{\mt{Type}\} \times \{\mt{Type}\})\} \\ \hspace{.1in} \to \mt{sql\_subset} \\ - \hspace{.2in} (\mt{fold} \; (\lambda \mt{nm} \; (\mt{fields} :: (\{\mt{Type}\} \times \{\mt{Type}\})) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \; [\mt{fields}.1 \sim \mt{fields}.2] \Rightarrow \\ - \hspace{.3in} [\mt{nm} = \mt{fields}.1 \rc \mt{fields}.2] \rc \mt{acc}) \; [] \; \mt{keep\_drop}) \\ - \hspace{.2in} (\mt{fold} \; (\lambda \mt{nm} \; (\mt{fields} :: (\{\mt{Type}\} \times \{\mt{Type}\})) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{fields}.1] \rc \mt{acc}) \; [] \; \mt{keep\_drop}) \\ + \hspace{.2in} (\mt{map} \; (\lambda \mt{fields} :: (\{\mt{Type}\} \times \{\mt{Type}\}) \Rightarrow \mt{fields}.1 \rc \mt{fields}.2)\; \mt{keep\_drop}) \\ + \hspace{.2in} (\mt{map} \; (\lambda \mt{fields} :: (\{\mt{Type}\} \times \{\mt{Type}\}) \Rightarrow \mt{fields}.1) \; \mt{keep\_drop}) \\ \mt{val} \; \mt{sql\_subset\_all} : \mt{tables} :: \{\{\mt{Type}\}\} \to \mt{sql\_subset} \; \mt{tables} \; \mt{tables} \end{array}$$ @@ -1363,13 +1375,13 @@ $$\begin{array}{l} Properly-typed records may be used to form $\mt{INSERT}$ commands. $$\begin{array}{l} \mt{val} \; \mt{insert} : \mt{fields} ::: \{\mt{Type}\} \to \mt{sql\_table} \; \mt{fields} \\ - \hspace{.1in} \to \$(\mt{fold} \; (\lambda \mt{nm} \; (\mt{t} :: \mt{Type}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{sql\_exp} \; [] \; [] \; [] \; \mt{t}] \rc \mt{acc}) \; [] \; \mt{fields}) \to \mt{dml} + \hspace{.1in} \to \$(\mt{map} \; (\mt{sql\_exp} \; [] \; [] \; []) \; \mt{fields}) \to \mt{dml} \end{array}$$ An $\mt{UPDATE}$ command is formed from a choice of which table fields to leave alone and which to change, along with an expression to use to compute the new value of each changed field and a $\mt{WHERE}$ clause. $$\begin{array}{l} \mt{val} \; \mt{update} : \mt{unchanged} ::: \{\mt{Type}\} \to \mt{changed} :: \{\mt{Type}\} \to \lambda [\mt{changed} \sim \mt{unchanged}] \\ - \hspace{.1in} \Rightarrow \$(\mt{fold} \; (\lambda \mt{nm} \; (\mt{t} :: \mt{Type}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; [] \; \mt{t}] \rc \mt{acc}) \; [] \; \mt{changed}) \\ + \hspace{.1in} \Rightarrow \$(\mt{map} \; (\mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; []) \; \mt{changed}) \\ \hspace{.1in} \to \mt{sql\_table} \; (\mt{changed} \rc \mt{unchanged}) \to \mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; [] \; \mt{bool} \to \mt{dml} \end{array}$$ diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs index c2a55168..e4bff8a9 100644 --- a/lib/ur/basis.urs +++ b/lib/ur/basis.urs @@ -128,12 +128,12 @@ val sql_query1 : tables ::: {{Type}} -> grouped ::: {{Type}} -> selectedFields ::: {{Type}} -> selectedExps ::: {Type} - -> {From : $(map (fn fields :: {Type} => sql_table fields) tables), + -> {From : $(map sql_table tables), Where : sql_exp tables [] [] bool, GroupBy : sql_subset tables grouped, Having : sql_exp grouped tables [] bool, SelectFields : sql_subset grouped selectedFields, - SelectExps : $(map (fn (t :: Type) => sql_exp grouped tables [] t) selectedExps) } + SelectExps : $(map (sql_exp grouped tables []) selectedExps) } -> sql_query1 tables selectedFields selectedExps type sql_relop |