switch to simpler cargo-like modes

doc/cli-design.txt

@@ -2,13 +2,13 @@ A flexible music programming language powered by math.
 
 usage:
 
-cmd [FILENAME | -c SHEET_MUSIC | --syntax | --examples | --example <n>] [-e EXPR] [-l EXPR] -n NOTE[,...] [-E [-f {"stdout" | FORMAT}]] [-v CHAR=VALUE]
+blip [play [FILENAME | -c SHEET_MUSIC] [-e EXPR] [-l EXPR] -n NOTE[,...] [-v CHAR=VALUE] | export [FILENAME | -c SHEET_MUSIC] [-e EXPR] [-l EXPR] -n NOTE[,...] [-v CHAR=VALUE] [-f FORMAT] [-o FILENAME] | help [syntax | examples | example <n> | formats]]
 
-arguments:
-    FILENAME        file path to your .blp sheet music  [default: read from stdin]
 
-options:
-    playing music:
+modes:
+    play - play a song
+        FILENAME
+            name of the file to use as the sheet music [default: standard in]
         -c SHEET_MUSIC
             sheet music to read instead of reading a file
         -n NOTE[,...], --notes NOTE[,...]
@@ -17,14 +17,6 @@ options:
             signal expression (instrument) to generate music samples (you can use the floating-point number t for the current time in seconds, n for the indice of the currently playing note in the list of available notes starting with 0 and N for the number of available notes)  [default: "sin(2*PI*(442+442*((n+1)/N))*t)"]
         -l EXPR, --length EXPR
             expression to generate note length in seconds  [default: "2^(2-log_2(l))*(60/T)"]
-
-    exporting music:
-        -E, --export
-            export audio instead of playing it
-        -f, --format
-            audio format to use for exporting with -E
-
-    advanced sheet music tweaking:
         -v VARIABLE=VALUE, --variable VARIABLE=VALUE
             add a variable named VARIABLE (an single letter) for the sheet music and all expressions and set its initial value to VALUE (you can override n, t, l and T which is the only way to set the initial tempo)
         -m NAME:EXPANSION, --macro MACRO:EXPANSION
@@ -32,10 +24,35 @@ options:
         -s NAME:VARIABLE=EXPR, --slope VARIABLE=EXPR
             add a slope expression named NAME which replaces the value of VARIABLE with the result of EXPR each frame (EXPR can use all available variables and instrument variables plus the variables α for the initial value of VARIABLE, β for the final value and Δ for the total duration of the specific slope)
 
-    help:
-        --syntax
+    export - export a song to an audio file or stdout
+        FILENAME
+            name of the file to use as the sheet music [default: standard in]
+        -c SHEET_MUSIC
+            sheet music to read instead of reading a file
+        -n NOTE[,...], --notes NOTE[,...]
+            available notes: a list of comma-separated alphabetical note names
+        -e EXPR, --expression EXPR
+            signal expression (instrument) to generate music samples (you can use the floating-point number t for the current time in seconds, n for the indice of the currently playing note in the list of available notes starting with 0 and N for the number of available notes)  [default: "sin(2*PI*(442+442*((n+1)/N))*t)"]
+        -l EXPR, --length EXPR
+            expression to generate note length in seconds  [default: "2^(2-log_2(l))*(60/T)"]
+        -v VARIABLE=VALUE, --variable VARIABLE=VALUE
+            add a variable named VARIABLE (an single letter) for the sheet music and all expressions and set its initial value to VALUE (you can override n, t, l and T which is the only way to set the initial tempo)
+        -m NAME:EXPANSION, --macro MACRO:EXPANSION
+            add a macro named NAME (single character, must not be alphanumeric) which expands to EXPANSION when called in the sheet music
+        -s NAME:VARIABLE=EXPR, --slope VARIABLE=EXPR
+            add a slope expression named NAME which replaces the value of VARIABLE with the result of EXPR each frame (EXPR can use all available variables and instrument variables plus the variables α for the initial value of VARIABLE, β for the final value and Δ for the total duration of the specific slope)
+        -f, --format FORMAT
+            audio format to use [default: mp3 or raw if the codec is unavailable]
+            see "help formats"
+        -o, --output FILENAME
+            output file [default: standard out]
+            
+    help - help menu
+        syntax
             show a help message about expression and sheet music syntax
-        --examples
+        examples
             show a list of expression and sheet music examples
-        --example <n>
+        example <n>
             show the nth example from the list provided by --examples
+        formats
+            show a list of available formats for audio export