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https://github.com/idris-lang/Idris2.git
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[ doc ] Add missing pragmas to documentation
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@ -182,6 +182,8 @@ custom back-end and diverging from the Idris representation is not a good idea.
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The best approach here is to build a conversion layer between the string
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representation of the custom back-end and the runtime.
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.. _sect-world:
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**World**
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In pure functional programming, causality needs to be represented whenever we
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@ -1,3 +1,5 @@
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.. _ffi-overview:
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************
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FFI Overview
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************
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@ -253,6 +253,8 @@ Once we know what the bound implicits need to be, we bind them in
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gets turned into a local binding (either Pi or Pat as appropriate, or PLet for
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@-patterns).
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.. _unbound-implicits:
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Unbound Implicits
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-----------------
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@ -10,6 +10,7 @@ The compiler has the ``--timing`` flag to dump timing information collected duri
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The output documents, in reverse chronological order, the cumulative time taken for the operation (and sub operations) to complete.
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Sub levels are indicated by successive repetitions of ``+``.
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.. _sect-logging:
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Logging
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=======
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@ -14,17 +14,127 @@ small niche of pragmas apply directly to one or more arguments instead of the co
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This page is a work in progress. If you know about a pragma that is not described yet, please consider
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submitting a pull request!
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Global pragmas
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====================
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``%language``
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--------------------
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Enable language extensions. Currently, the only extension is ``ElabReflection``.
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.. code-block:: idris
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%language ElabReflection
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``%default``
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--------------------
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Set the default totality requirement for functions. The initial value is `covering`, which
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required case statements to cover, but does not require totality. The other options are
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`total` and `partial`.
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``%builtin``
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====================
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--------------------
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The ``%builtin Natural`` pragma converts recursive/unary representations of natural numbers
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into primitive ``Integer`` representations.
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This pragma is explained in detail on its own page. For more, see :ref:`builtins`.
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``%name``
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--------------------
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Give the compiler some suggested names to use for a particular type when it is asked to generate names for values.
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You can specify any number of suggested names; they will be used in-order when more than one is needed for a single
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definition.
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.. code-block:: idris
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data Foo = X | Y
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%name Foo foo,bar
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``%ambiguity_depth``
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--------------------
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Set how deep nested ambiguous names can be before Idris gives up. The default is 3, increashing this
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will effect compiler performance. For more details, see :ref:`ambiguous-name-resolution`.
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``%auto_implicit_depth``
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------------------------
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Set the search depth for ``auto`` implicits. The default value is 50.
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``%logging``
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--------------------
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Change the logging level. See :ref:`sect-logging` for details.
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.. code-block:: idris
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%logging 1
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%logging "elab" 5
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``%prefix_record_projections``
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------------------------------
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Configure whether projection functions without a leading period are generated for records. It defaults
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to ``on``. See :ref:`record-elaboration` for more details.
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.. code-block:
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%prefix_record_projections on
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``%transform``
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--------------------
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Replace a function at runtime with another implementation. It allows us to
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functions that are appropriate for type checking and have an efficient version at runtime. For example:
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.. code-block:: idris
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plus : Nat -> Nat -> Nat
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plus Z y = y
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plus (S x) y = S $ plus x y
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%transform "plus" plus j k = integerToNat (natToInteger j + natToInteger j)
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``%unbound_implicits``
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----------------------
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Configure whether implicit bindings are automatically added to function types for unbound
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lowercase names. It is on by default. See :ref:`unbound-implicits` for more details.
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``%auto_lazy``
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--------------------
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Configure whether the compiler automatically adds ``delay`` and ``force`` when
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necessary. It defaults to ``on``.
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``%search_timeout``
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--------------------
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Set the expression search timeout in milliseconds. The default is 1000.
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.. code-block:: idris
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%search_timeout 1000
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``%nf_metavar_threshold``
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-------------------------
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Set the maximum number of stuck applications allowed while unifying a meta. The
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default value is 25.
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Pragmas on declarations
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=======================
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``%deprecate``
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====================
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--------------------
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Mark the following definition as deprecated. Whenever the function is used, Idris will show a deprecation
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warning.
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@ -61,10 +171,10 @@ deprecated function call and that documentation will be displayed alongside the
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Please use the @altFoo@ function from now on.
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``%inline``
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====================
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--------------------
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Instruct the compiler to inline the following definition when it is applied. It is generally best to let the
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compiler and the backend you are using optimize code based on its predetermined rules, but if you want to
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compiler and the backend you are using optimise code based on its predetermined rules, but if you want to
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force a function to be inlined when it is called, this pragma will force it.
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.. code-block:: idris
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@ -74,10 +184,10 @@ force a function to be inlined when it is called, this pragma will force it.
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foo x = x ++ "!"
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``%noinline``
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====================
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--------------------
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Instruct the compiler _not_ to inline the following definition when it is applied. It is generally best to let the
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compiler and the backend you are using optimize code based on its predetermined rules, but if you want to
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compiler and the backend you are using optimise code based on its predetermined rules, but if you want to
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force a function to never be inlined when it is called, this pragma will force it.
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.. code-block:: idris
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@ -86,21 +196,13 @@ force a function to never be inlined when it is called, this pragma will force i
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foo : String -> String
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foo x = x ++ "!"
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``%name``
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====================
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``%tcinline``
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--------------------
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Give the compiler some suggested names to use for a particular type when it is asked to generate names for values.
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You can specify any number of suggested names; they will be used in-order when more than one is needed for a single
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definition.
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.. code-block:: idris
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data Foo = X | Y
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%name Foo foo,bar
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Instruct the compiler to inline the function during totality checking.
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``%hide``
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====================
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--------------------
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Hide a definition from imports. This is particularly useful when you are re-definiing functions or types from
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a module but still need to import it.
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@ -124,3 +226,247 @@ You can also hide fixity declarations if you need to redefine your own.
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%hide Prelude.Ops.infixl.(+)
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infixr 5 +
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``%unhide``
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--------------------
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The ``%unhide`` pragma unhides a definition that was previously hidden with ``%hide``.
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``%unsafe``
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--------------------
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Mark a function like ``believe_me`` as being unsafe. The function will be semantically
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highlighted in a different color to draw the user's attention to its use.
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``%spec``
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--------------------
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Specialise a function according to a list of arguments.
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.. code-block:: idris
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%spec a
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identity : List a -> List a
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identity [] = []
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identity (x :: xs) = x :: identity xs
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``%foreign``
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--------------------
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Declare a foreign function. It is followed by an indented block of expressions
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that evaluate to strings. See :ref:`ffi-overview` for more details.
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``%export``
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--------------------
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Export an Idris function to the underlying host language. The the name for each backend is
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given in an indented block of string expressions, similar to ``%foreign``. Currently this
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pragma is only supported by the javascript backend.
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.. code-block:: idris
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%export "javascript:addNat"
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addNat : Nat -> Nat -> Nat
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addNat a b = a + b
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``%nomangle``
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--------------------
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This pragma is deprecated. Instead use ``%export`` to expose functions to the backend.
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``%hint``
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--------------------
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Mark a function to be used for ``auto`` search (see :ref:`auto-implicits` for more).
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``%defaulthint``
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--------------------
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Mark a default for functions like ``fromString`` in cases where the compiler cannot
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determine which type the user wants.
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``%globalhint``
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--------------------
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This pragma is similar to ``%defaulthint``.
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``%extern``
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--------------------
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Declare a function to be externally implemented, but relies on codegen
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to fill in the function rather than specifying the name. The function name must be explicitly
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handled in the codegen. It is used for functions like ``prim__newIORef`` in the prelude.
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``%macro``
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--------------------
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Mark a function that returns the ``Elab`` monad as a macro. When the function is used in
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an expression, it will be run at compile time and the invocation will be replaced by the
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result of the elaboration.
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``%start``
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--------------------
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The ``%start`` pragma is not implemented.
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``%allow_overloads``
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--------------------
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This pragma is no longer used by the compiler.
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Internal
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========
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These pragmas are used in the prelude, but aren't typically used in user programs.
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``%rewrite``
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--------------------
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Specify the `Equal` type and rewrite function used by rewrite statements.
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.. code-block:: idris
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%rewrite Equal rewrite__impl
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``%pair``
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--------------------
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This directive is used in the prelude to tell auto implicit search what to use to look inside pairs.
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.. code-block:: idris
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%pair Pair fst snd
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``%integerLit``
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--------------------
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Define the function used to interpret literal integers. In the prelude, it is set
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to ``fromInteger``, so a literal ``2`` is elaborated to ``fromInteger 2``.
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.. code-block:: idris
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%integerLit fromInteger
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``%stringLit``
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--------------------
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Define the function used to interpret literal strings. In the prelude, it is set
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to ``fromString``, so a literal ``"idris"`` is elaborated to ``fromString "idris"``.
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.. code-block:: idris
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%stringLit fromString
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``%charLit``
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--------------------
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Define the function used to interpret literal characters. In the prelude, it is set
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to ``fromChar``, so a literal ```x```` is elaborated to ``fromChar 'x'``.
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.. code-block:: idris
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%charLit fromChar
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``%doubleLit``
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--------------------
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Define the function used to interpret literal numbers with a decimal in them. In the prelude, it is set
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to ``fromDouble``, so a literal ```2.0```` is elaborated to ``fromDouble 2.0``.
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.. code-block:: idris
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%charLit fromDouble
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Reflection Literals
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===================
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``%TTImpLit``
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--------------------
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Allow quoted expressions to be cast to a user defined type.
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.. code-block:: idris
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%TTImpLit fromTTImp
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public export
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data NatExpr : Type where
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Plus : NatExpr -> NatExpr -> NatExpr
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Mult : NatExpr -> NatExpr -> NatExpr
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Val : Nat -> NatExpr
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Var : String -> NatExpr
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public export
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natExpr : TTImp -> Elab NatExpr
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natExpr `(~(l) + ~(r)) = [| Plus (natExpr l) (natExpr r) |]
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natExpr `(~(l) * ~(r)) = [| Mult (natExpr l) (natExpr r) |]
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natExpr `(fromInteger ~(IPrimVal _ (BI n))) = pure $ Val $ fromInteger n
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natExpr (IVar _ (UN (Basic nm))) = pure $ Var nm
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natExpr s = failAt (getFC s) "Invalid NatExpr"
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%macro
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fromTTImp : TTImp -> Elab NatExpr
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fromTTImp = natExpr
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export
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natExprMacroTest : NatExpr
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natExprMacroTest = `(1 + 2 + x)
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``%declsLit``
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--------------------
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Allow quoted declarations to be cast to user defined types.
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``%nameLit``
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--------------------
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Allow quoted names to be cast to user defined types.
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Expressions
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===========
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Pragmas that occur inside expressions.
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``%runElab``
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--------------------
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The ``%runElab`` pragma can be used at the top level or as an expression. It takes the an elaboration
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script as an argument which runs in the ``Elab`` monad, has access to Idris' type-checking machinery,
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and can generate code.
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``%search``
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--------------------
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Ask Idris to fill in the value with auto-implicit search. See :ref:`auto-implicits` for more details.
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``%World``
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--------------------
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The type of the world token used for IO. For more information, see :ref:`World<sect-world>`.
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``%MkWorld``
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--------------------
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The world token used for IO. For more information, see :ref:`World<sect-world>`.
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``%syntactic``
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--------------------
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The ``%syntactic`` pragma can appear after the ``with`` keyword. It abstracts
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over the value syntactically, rather than by value, and can significantly speed
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up elaboration where large types are involved, at a cost of being less general.
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Try it if "with" is slow.
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@ -50,6 +50,8 @@ Desugaring rules
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* ``(simpleExpr .field1 .field2 .field3)`` desugars to ``((.field .field2
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.field3) simpleExpr)``
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.. _record-elaboration:
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Record elaboration
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------------------
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|
@ -245,6 +245,8 @@ in the prelude in:
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Smaller Changes
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===============
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.. _ambiguous-name-resolution:
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Ambiguous Name Resolution
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-------------------------
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@ -360,6 +362,8 @@ below.
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Also, an alternative syntax ``let x := val in e`` is available.
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See Section :ref:`sect-let-bindings` for more info.
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.. _auto-implicits:
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``auto``-implicits and Interfaces
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---------------------------------
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Loading…
Reference in New Issue
Block a user