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Diffstat (limited to 'm.html.markdown')
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1 files changed, 34 insertions, 33 deletions
diff --git a/m.html.markdown b/m.html.markdown index 3ea422c4..a3885d6d 100644 --- a/m.html.markdown +++ b/m.html.markdown @@ -1,8 +1,8 @@ ---- +--- language: M (MUMPS) -contributors: - - ["Fred Turkington", "http://z3ugma.github.io"] -filename: LEARNM.m +contributors: + - ["Fred Turkington", "http://z3ugma.github.io"] +filename: LEARNM.m --- M, or MUMPS (Massachusetts General Hospital Utility Multi-Programming System) is @@ -22,7 +22,7 @@ to modern formats like JSON. Originally designed in 1966 for the healthcare applications, M continues to be used widely by healthcare systems and financial institutions for high-throughput -real-time applications. +real-time applications. ### Example @@ -72,12 +72,12 @@ Commands are case insensitive, and have full form, and a shortened abbreviation, #### Common Commands from all National and International Standards of M -#### Write (abbreviated as W) +#### Write (abbreviated as W) Print data to the current device. -``` -WRITE !,"hello world" +``` +WRITE !,"hello world" ``` Output Formatting characters: @@ -89,7 +89,7 @@ Output Formatting characters: Multiple statements can be provided as additional arguments before the space separators to the next command: ``` -w !,"foo bar"," ","baz" +w !,"foo bar"," ","baz" ``` #### Read (abbreviated as R) @@ -124,7 +124,7 @@ w !,centi,!,micro Remove a variable from memory or remove a database entry from disk. A database node (global variable) is killed depending on the variable name being prefixed by the caret character (^). -If it is not, then the local variable is removed from memory. +If it is not, then the local variable is removed from memory. If KILLed, automatic garbage collection occurs. ``` @@ -134,9 +134,9 @@ k micro ### Globals and Arrays -In addition to local variables, M has persistent, shared variables that are the built-in database of M. They are stored to disk and called _globals_. Global names must start with a __caret__ (__^__). +In addition to local variables, M has persistent, shared variables that are the built-in database of M. They are stored to disk and called _globals_. Global names must start with a __caret__ (__^__). -Any variable (local or global) can be an array with the assignment of a _subscript_. Arrays are sparse and do not have a predefined size. Only if data is stored will a value use memory. Arrays should be visualized like trees, where subscripts are branches and assigned values are leaves. Not all nodes in an array need to have a value. +Any variable (local or global) can be an array with the assignment of a _subscript_. Arrays are sparse and do not have a predefined size. Only if data is stored will a value use memory. Arrays should be visualized like trees, where subscripts are branches and assigned values are leaves. Not all nodes in an array need to have a value. ``` s ^cars=20 @@ -144,7 +144,7 @@ s ^cars("Tesla",1,"Name")="Model 3" s ^cars("Tesla",2,"Name")="Model X" s ^cars("Tesla",2,"Doors")=5 -w !,^cars +w !,^cars ; 20 w !,^cars("Tesla") ; null value - there's no value assigned to this node but it has children @@ -164,23 +164,23 @@ s ^TEMPS("11/12","1700",43)="" ### Operators -```jinja +``` ; Assignment: = ; Unary: + Convert a string value into a numeric value. ; Arthmetic: ; + addition -; - subtraction +; - subtraction ; * multiplication ; / floating-point division ; \ integer division ; # modulo ; ** exponentiation -; Logical: +; Logical: ; & and ; ! or ; ' not ; Comparison: -; = equal +; = equal ; '= not equal ; > greater than ; < less than @@ -188,7 +188,7 @@ s ^TEMPS("11/12","1700",43)="" ; '< not less / greater than or equal to ; String operators: ; _ concatenate -; [ contains a contains b +; [ contains a contains b ; ]] sorts after a comes after b ; '[ does not contain ; ']] does not sort after @@ -204,7 +204,7 @@ To change this order, just use parentheses to group expressions to be evaluated w 5+3*20 ;160 ;You probably wanted 65 -write 5+(3*20) +write 5+(3*20) ``` ### Flow Control, Blocks, & Code Structure @@ -215,17 +215,17 @@ A tag can accept parameters and return a value, this is a function. A function i ``` ; Execute the 'tag' function, which has two parameters, and write the result. -w !,$$tag^routine(a,b) +w !,$$tag^routine(a,b) ``` M has an execution stack. When all levels of the stack have returned, the program ends. Levels are added to the stack with _do_ commands and removed with _quit_ commands. #### Do (abbreviated as D) -With an argument: execute a block of code & add a level to the stack. +With an argument: execute a block of code & add a level to the stack. ``` -d ^routine ;run a routine from the beginning. +d ^routine ;run a routine from the beginning. ; ;routines are identified by a caret. d tag ;run a tag in the current routine d tag^routine ;run a tag in different routine @@ -235,11 +235,11 @@ Argumentless do: used to create blocks of code. The block is indented with a per ``` set a=1 -if a=1 do +if a=1 do . write !,a . read b . if b > 10 d -. . w !, b +. . w !, b w "hello" ``` @@ -258,7 +258,7 @@ Putting all this together, we can create a full example of an M routine: ; RECTANGLE - a routine to deal with rectangle math q ; quit if a specific tag is not called -main +main n length,width ; New length and width so any previous value doesn't persist w !,"Welcome to RECTANGLE. Enter the dimensions of your rectangle." r !,"Length? ",length,!,"Width? ",width @@ -267,7 +267,7 @@ main w !,"Perimeter: ",per quit -area(length,width) ; This is a tag that accepts parameters. +area(length,width) ; This is a tag that accepts parameters. ; It's not a function since it quits with no value. w !, "Area: ",length*width q ; Quit: return to the previous level of the stack. @@ -287,11 +287,11 @@ F(or) loops can follow a few different patterns: ;f var=start:increment:stop f i=0:5:25 w i," " -;0 5 10 15 20 25 +;0 5 10 15 20 25 ; Infinite loop with counter ; The counter will keep incrementing forever. Use a conditional with Quit to get out of the loop. -;f var=start:increment +;f var=start:increment f j=1:1 w j," " i j>1E3 q ; Print 1-1000 separated by a space @@ -299,7 +299,7 @@ f j=1:1 w j," " i j>1E3 q ;Argumentless for - infinite loop. Use a conditional with Quit. ; Also read as "forever" - f or for followed by two spaces. s var="" -f s var=var_"%" w !,var i var="%%%%%%%%%%" q +f s var=var_"%" w !,var i var="%%%%%%%%%%" q ; % ; %% ; %%% @@ -371,7 +371,7 @@ f s date=$ORDER(^TEMPS(date)) q:date="" d . f s time=$O(^TEMPS(date,time)) q:time="" d . . w !,"Time: ",time -; Build an index that sorts first by temperature - +; Build an index that sorts first by temperature - ; what dates and times had a given temperature? n date,time,temp f s date=$ORDER(^TEMPS(date)) q:date="" d @@ -387,20 +387,21 @@ f s date=$ORDER(^TEMPS(date)) q:date="" d ## Further Reading -There's lots more to learn about M. A great short tutorial comes from the University of Northern Iowa and Professor Kevin O'Kane's [Introduction to the MUMPS Language][1] presentation. More about M using VistA is at +There's lots more to learn about M. A great short tutorial comes from the University of Northern Iowa and Professor Kevin O'Kane's [Introduction to the MUMPS Language][1] presentation. More about M using VistA is at Intersystems has some products which are a super-set of the M programming language. + * [Iris Description Page][5] * [Cache Description Page][6] -To install an M interpreter / database on your computer, try a [YottaDB Docker image][2]. +To install an M interpreter / database on your computer, try a [YottaDB Docker image][2]. YottaDB and its precursor, GT.M, have thorough documentation on all the language features including database transactions, locking, and replication: * [YottaDB Programmer's Guide][3] * [GT.M Programmer's Guide][4] -[1]: https://www.cs.uni.edu/~okane/source/MUMPS-MDH/MumpsTutorial.pdf +[1]: https://www.cs.uni.edu/~okane/source/MUMPS-MDH/MumpsTutorial.pdf [2]: https://yottadb.com/product/get-started/ [3]: https://docs.yottadb.com/ProgrammersGuide/langfeat.html [4]: http://tinco.pair.com/bhaskar/gtm/doc/books/pg/UNIX_manual/index.html |