ProgTutorial/FirstSteps.thy
changeset 279 2927f205abba
parent 277 cc862fd5e0cb
child 280 a63ca3a9b44a
equal deleted inserted replaced
278:c6b64fa9f301 279:2927f205abba
  1549 *}
  1549 *}
  1550 
  1550 
  1551 ML{*val my_thms = ref ([] : thm list)*}
  1551 ML{*val my_thms = ref ([] : thm list)*}
  1552 
  1552 
  1553 text {* 
  1553 text {* 
  1554   The purpose of this reference is that we are going to add and delete theorems
  1554   The purpose of this reference is to store a list of theorems.
  1555   to the referenced list. However, a word of warning: such references must not 
  1555   We are going to modify it by adding and deleting theorems.
       
  1556   However, a word of warning: such references must not 
  1556   be used in any code that is meant to be more than just for testing purposes! 
  1557   be used in any code that is meant to be more than just for testing purposes! 
  1557   Here it is only used to illustrate matters. We will show later how to store 
  1558   Here it is only used to illustrate matters. We will show later how to store 
  1558   data properly without using references.
  1559   data properly without using references.
  1559  
  1560  
  1560   We need to provide two functions that add and delete theorems from this list. 
  1561   We need to provide two functions that add and delete theorems from this list.