Logikoma
221ed7219d
Reflow the approved reference cases, shorten local fixture comments, and split the executable docs line so the 80-byte input buffer can read every source line. Co-authored-by: andrew <andrew@aklabs.net>
24 lines
1.0 KiB
QBasic
24 lines
1.0 KiB
QBasic
10 REM A DEF call takes an environment from the pool, one per call, exactly as
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20 REM GOSUB does. It used to be owned by the funcdef and reset on every call,
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30 REM which cost two silent defects: two calls shared a slot,
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40 REM and recursion never came back at all.
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50 DEF FACT(N#)
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60 IF N# <= 1 THEN RETURN 1
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70 RETURN N# * FACT(N# - 1)
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80 PRINT FACT(5)
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90 REM Each frame keeps its own argument, which is what makes the unwind work.
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100 DEF SUMTO(N#)
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110 IF N# <= 0 THEN RETURN 0
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120 RETURN N# + SUMTO(N# - 1)
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130 PRINT SUMTO(4)
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140 REM And two calls to one function in one expression no longer collide.
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150 DEF DBL(N#) = N# * 2
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160 PRINT DBL(10) + DBL(1)
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170 PRINT DBL(1) + DBL(10) + DBL(100)
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180 REM Depth answers to the pool, so runaway recursion reports
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190 REM "Environment pool exhausted" rather than hanging. It is not exercised
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200 REM here because a failed call's statement still prints a junk value
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210 REM afterwards -- a TODO.md defect this file would pin
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220 REM if it went in. tests/user_functions.c asserts
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230 REM the message instead.
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