IN: namespaces
USING: help ;

HELP: get "( variable -- value )"
{ $values { "variable" "a variable, by convention a symbol" } { "value" "the value, or " { $link f } } }
{ $description "Searches the namestack for a namespace containing the variable, and outputs the associated value. If no such namespace is found, outputs " { $link f } "." } ;

HELP: set "( value variable -- )"
{ $values { "value" "the new value" } { "variable" "a variable, by convention a symbol" } }
{ $description "Assigns a value to the variable in the namespace at the top of the namestack." }
{ $side-effects "variable" } ;

HELP: off "( variable -- )"
{ $values { "variable" "a variable, by convention a symbol" } }
{ $description "Assigns a value of " { $link f } " to the variable." }
{ $side-effects "variable" } ;

HELP: on "( variable -- ) "
{ $values { "variable" "a variable, by convention a symbol" } }
{ $description "Assigns a value of " { $link t } " to the variable." }
{ $side-effects "variable" } ;

HELP: change "( variable quot -- )"
{ $values { "variable" "a variable, by convention a symbol" } { "quot" "a quotation with stack effect " { $snippet "( old -- new )" } } }
{ $description "Applies the quotation to the old value of the variable, and assigns the resulting value to the variable." }
{ $side-effects "variable" } ;

HELP: inc "( variable -- ) "
{ $values { "variable" "a variable, by convention a symbol" } }
{ $description "Increments the value of the variable by 1." }
{ $errors "An error is thrown if the variable does not hold a number." }
{ $side-effects "variable" } ;

HELP: dec "( variable -- ) "
{ $values { "variable" "a variable, by convention a symbol" } }
{ $description "Decrements the value of the variable by 1." }
{ $errors "An error is thrown if the variable does not hold a number." }
{ $side-effects "variable" } ;

HELP: with-scope "( quot -- )"
{ $values { "quot" "a quotation" } }
{ $description "Calls the quotation in a new namespace. Any variables set by the quotation are discarded when it returns." } ;

HELP: make-hash "( quot -- hash )"
{ $values { "quot" "a quotation" } { "hash" "a new hashtable" } }
{ $description "Calls the quotation in a new namespace, and outputs this namespace when the quotation returns. Useful for quickly building hashtables." } ;

HELP: bind "( ns quot -- )"
{ $values { "ns" "a hashtable" } { "quot" "a quotation" } }
{ $description "Calls the quotation in the dynamic scope of " { $snippet "ns" } ". When variables are looked up by the quotation, " { $snippet "ns" } " is checked first, and setting variables in the quotation stores them in " { $snippet "ns" } "." } ;

HELP: namespace "( -- ns )"
{ $values { "ns" "a hashtable" } }
{ $description "Outputs the current namespace. Calls to " { $link set } " modify this namespace." } ;

HELP: global "( -- ns )"
{ $values { "ns" "a hashtable" } }
{ $description "Outputs the global namespace. The global namespace is always checked last when looking up variable values." } ;

HELP: set-global "( value variable -- )"
{ $values { "value" "the new value" } { "variable" "a variable, by convention a symbol" } }
{ $description "Assigns a value to the variable in the global namespace." }
{ $side-effects "variable" } ;

HELP: nest "( variable -- namespace )"
{ $values { "variable" "a variable, by convention a symbol" } { "namespace" "a hashtable" } }
{ $description "If the variable is not set in the current namespace, sets it to a new hashtable, and outputs this hashtable. Otherwise, outputs the existing value (which should probably be a hashtable)." }
{ $side-effects "variable" } ;

HELP: namestack* "( -- namestack )"
{ $values { "namestack" "a vector" } }
{ $description "Outputs the current namestack." } ;

HELP: namestack "( -- namestack )"
{ $values { "namestack" "a vector" } }
{ $description "Outputs a copy of the current namestack." } ;

HELP: set-namestack "( namestack -- )"
{ $values { "namestack" "a vector" } }
{ $description "Replaces the namestack with a copy of the given vector." } ;

HELP: >n "( ns -- )"
{ $values { "ns" "a hashtable" } }
{ $description "Pushes a namespace on the namestack." } ;

HELP: n> "( -- ns )"
{ $values { "ns" "a hashtable" } }
{ $description "Pops a namespace from the namestack." } ;

HELP: make "( quot exemplar -- seq )"
{ $values { "quot" "a quotation" } { "exemplar" "a sequence" } }
{ $description "Calls the quotation in a new " { $emphasis "dynamic scope" } ". The quotation and any words it calls can execute the " { $link , } " and " { $link % } " words to accumulate elements. When the quotation returns, all accumulated elements are collected into a sequence with the same type as " { $snippet "exemplar" } "." }
{ $examples { $example "[ 1 , 2 , 3 , ] { } make ." "{ 1 2 3 }" } } ;

HELP: , "( elt -- )"
{ $values { "elt" "an object" } }
{ $description "Adds an element to the end of the sequence being constructed by " { $link make } "." } ;

HELP: % "( seq -- )"
{ $values { "seq" "a sequence" } }
{ $description "Appends a sequence to the end of the sequence being constructed by " { $link make } "." } ;

HELP: # "( n -- )"
{ $values { "n" "a real number" } }
{ $description "Appends the string representation of a real number to the end of the sequence being constructed by " { $link make } "." } ;